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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
VI(1P) POSIX Programmer's Manual VI(1P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
vi — screen-oriented (visual) display editor
vi [−rR] [−c command] [−t tagstring] [−w size] [file...]
This utility shall be provided on systems that both support the User
Portability Utilities option and define the POSIX2_CHAR_TERM symbol.
On other systems it is optional.
The vi (visual) utility is a screen-oriented text editor. Only the
open and visual modes of the editor are described in POSIX.1‐2008;
see the line editor ex for additional editing capabilities used in
vi. The user can switch back and forth between vi and ex and execute
ex commands from within vi.
This reference page uses the term edit buffer to describe the current
working text. No specific implementation is implied by this term. All
editing changes are performed on the edit buffer, and no changes to
it shall affect any file until an editor command writes the file.
When using vi, the terminal screen acts as a window into the editing
buffer. Changes made to the editing buffer shall be reflected in the
screen display; the position of the cursor on the screen shall
indicate the position within the editing buffer.
Certain terminals do not have all the capabilities necessary to
support the complete vi definition. When these commands cannot be
supported on such terminals, this condition shall not produce an
error message such as ``not an editor command'' or report a syntax
error. The implementation may either accept the commands and produce
results on the screen that are the result of an unsuccessful attempt
to meet the requirements of this volume of POSIX.1‐2008 or report an
error describing the terminal-related deficiency.
The vi utility shall conform to the Base Definitions volume of
POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines, except that
'+' may be recognized as an option delimiter as well as '−'.
The following options shall be supported:
−c command
See the ex command description of the −c option.
−r See the ex command description of the −r option.
−R See the ex command description of the −R option.
−t tagstring
See the ex command description of the −t option.
−w size See the ex command description of the −w option.
See the OPERANDS section of the ex command for a description of the
operands supported by the vi command.
If standard input is not a terminal device, the results are
undefined. The standard input consists of a series of commands and
input text, as described in the EXTENDED DESCRIPTION section.
If a read from the standard input returns an error, or if the editor
detects an end-of-file condition from the standard input, it shall be
equivalent to a SIGHUP asynchronous event.
See the INPUT FILES section of the ex command for a description of
the input files supported by the vi command.
See the ENVIRONMENT VARIABLES section of the ex command for the
environment variables that affect the execution of the vi command.
See the ASYNCHRONOUS EVENTS section of the ex for the asynchronous
events that affect the execution of the vi command.
If standard output is not a terminal device, undefined results occur.
Standard output may be used for writing prompts to the user, for
informational messages, and for writing lines from the file.
If standard output is not a terminal device, undefined results occur.
The standard error shall be used only for diagnostic messages.
See the OUTPUT FILES section of the ex command for a description of
the output files supported by the vi command.
If the terminal does not have the capabilities necessary to support
an unspecified portion of the vi definition, implementations shall
start initially in ex mode or open mode. Otherwise, after
initialization, vi shall be in command mode; text input mode can be
entered by one of several commands used to insert or change text. In
text input mode, <ESC> can be used to return to command mode; other
uses of <ESC> are described later in this section; see Terminate
Command or Input Mode.
Initialization in ex and vi
See Initialization in ex and vi for a description of ex and vi
initialization for the vi utility.
Command Descriptions in vi
The following symbols are used in this reference page to represent
arguments to commands.
buffer See the description of buffer in the EXTENDED DESCRIPTION
section of the ex utility; see Command Descriptions in ex.
In open and visual mode, when a command synopsis shows both
[buffer] and [count] preceding the command name, they can be
specified in either order.
count A positive integer used as an optional argument to most
commands, either to give a repeat count or as a size. This
argument is optional and shall default to 1 unless otherwise
specified.
The Synopsis lines for the vi commands <control>‐G,
<control>‐L, <control>‐R, <control>‐], %, &, ^, D, m, M, Q,
u, U, and ZZ do not have count as an optional argument.
Regardless, it shall not be an error to specify a count to
these commands, and any specified count shall be ignored.
motion An optional trailing argument used by the !, <, >, c, d, and
y commands, which is used to indicate the region of text that
shall be affected by the command. The motion can be either
one of the command characters repeated or one of several
other vi commands (listed in the following table). Each of
the applicable commands specifies the region of text matched
by repeating the command; each command that can be used as a
motion command specifies the region of text it affects.
Commands that take motion arguments operate on either lines
or characters, depending on the circumstances. When operating
on lines, all lines that fall partially or wholly within the
text region specified for the command shall be affected. When
operating on characters, only the exact characters in the
specified text region shall be affected. Each motion command
specifies this individually.
When commands that may be motion commands are not used as
motion commands, they shall set the current position to the
current line and column as specified.
The following commands shall be valid cursor motion commands:
<apostrophe> ( - j H
<carriage-return> ) $ k L
<comma> [[ % l M
<control>-H ]] _ n N
<control>-N { ; t T
<control>-P } ? w W
<grave-accent> ^ b B
<newline> + e E
<space> | f F
<zero> / h G
Any count that is specified to a command that has an
associated motion command shall be applied to the motion
command. If a count is applied to both the command and its
associated motion command, the effect shall be
multiplicative.
The following symbols are used in this section to specify locations
in the edit buffer:
current character
The character that is currently indicated by the cursor.
end of a line
The point located between the last non-<newline> (if any) and
the terminating <newline> of a line. For an empty line, this
location coincides with the beginning of the line.
end of the edit buffer
The location corresponding to the end of the last line in the
edit buffer.
The following symbols are used in this section to specify command
actions:
bigword In the POSIX locale, vi shall recognize four kinds of
bigwords:
1. A maximal sequence of non-<blank> characters preceded and
followed by <blank> characters or the beginning or end of
a line or the edit buffer
2. One or more sequential blank lines
3. The first character in the edit buffer
4. The last non-<newline> in the edit buffer
word In the POSIX locale, vi shall recognize five kinds of words:
1. A maximal sequence of letters, digits, and underscores,
delimited at both ends by:
-- Characters other than letters, digits, or underscores
-- The beginning or end of a line
-- The beginning or end of the edit buffer
2. A maximal sequence of characters other than letters,
digits, underscores, or <blank> characters, delimited at
both ends by:
-- A letter, digit, underscore
-- <blank> characters
-- The beginning or end of a line
-- The beginning or end of the edit buffer
3. One or more sequential blank lines
4. The first character in the edit buffer
5. The last non-<newline> in the edit buffer
section boundary
A section boundary is one of the following:
1. A line whose first character is a <form-feed>
2. A line whose first character is an open curly brace ('{')
3. A line whose first character is a <period> and whose
second and third characters match a two-character pair in
the sections edit option (see ed)
4. A line whose first character is a <period> and whose only
other character matches the first character of a two-
character pair in the sections edit option, where the
second character of the two-character pair is a <space>
5. The first line of the edit buffer
6. The last line of the edit buffer if the last line of the
edit buffer is empty or if it is a ]] or } command;
otherwise, the last non-<newline> of the last line of the
edit buffer
paragraph boundary
A paragraph boundary is one of the following:
1. A section boundary
2. A line whose first character is a <period> and whose
second and third characters match a two-character pair in
the paragraphs edit option (see ed)
3. A line whose first character is a <period> and whose only
other character matches the first character of a two-
character pair in the paragraphs edit option, where the
second character of the two-character pair is a <space>
4. One or more sequential blank lines
remembered search direction
See the description of remembered search direction in ed.
sentence boundary
A sentence boundary is one of the following:
1. A paragraph boundary
2. The first non-<blank> that occurs after a paragraph
boundary
3. The first non-<blank> that occurs after a <period> ('.'),
<exclamation-mark> ('!'), or <question-mark> ('?'),
followed by two <space> characters or the end of a line;
any number of closing parenthesis (')'), closing brackets
(']'), double-quote ('"'), or single-quote (<apostrophe>)
characters can appear between the punctuation mark and
the two <space> characters or end-of-line
In the remainder of the description of the vi utility, the term
``buffer line'' refers to a line in the edit buffer and the term
``display line'' refers to the line or lines on the display screen
used to display one buffer line. The term ``current line'' refers to
a specific ``buffer line''.
If there are display lines on the screen for which there are no
corresponding buffer lines because they correspond to lines that
would be after the end of the file, they shall be displayed as a
single <tilde> ('~') character, plus the terminating <newline>.
The last line of the screen shall be used to report errors or display
informational messages. It shall also be used to display the input
for ``line-oriented commands'' (/, ?, :, and !). When a line-
oriented command is executed, the editor shall enter text input mode
on the last line on the screen, using the respective command
characters as prompt characters. (In the case of the ! command, the
associated motion shall be entered by the user before the editor
enters text input mode.) The line entered by the user shall be
terminated by a <newline>, a non-<control>‐V-escaped <carriage-
return>, or unescaped <ESC>. It is unspecified if more characters
than require a display width minus one column number of screen
columns can be entered.
If any command is executed that overwrites a portion of the screen
other than the last line of the screen (for example, the ex suspend
or ! commands), other than the ex shell command, the user shall be
prompted for a character before the screen is refreshed and the edit
session continued.
<tab> characters shall take up the number of columns on the screen
set by the tabstop edit option (see ed), unless there are less than
that number of columns before the display margin that will cause the
displayed line to be folded; in this case, they shall only take up
the number of columns up to that boundary.
The cursor shall be placed on the current line and relative to the
current column as specified by each command described in the
following sections.
In open mode, if the current line is not already displayed, then it
shall be displayed.
In visual mode, if the current line is not displayed, then the lines
that are displayed shall be expanded, scrolled, or redrawn to cause
an unspecified portion of the current line to be displayed. If the
screen is redrawn, no more than the number of display lines specified
by the value of the window edit option shall be displayed (unless the
current line cannot be completely displayed in the number of display
lines specified by the window edit option) and the current line shall
be positioned as close to the center of the displayed lines as
possible (within the constraints imposed by the distance of the line
from the beginning or end of the edit buffer). If the current line is
before the first line in the display and the screen is scrolled, an
unspecified portion of the current line shall be placed on the first
line of the display. If the current line is after the last line in
the display and the screen is scrolled, an unspecified portion of the
current line shall be placed on the last line of the display.
In visual mode, if a line from the edit buffer (other than the
current line) does not entirely fit into the lines at the bottom of
the display that are available for its presentation, the editor may
choose not to display any portion of the line. The lines of the
display that do not contain text from the edit buffer for this reason
shall each consist of a single '@' character.
In visual mode, the editor may choose for unspecified reasons to not
update lines in the display to correspond to the underlying edit
buffer text. The lines of the display that do not correctly
correspond to text from the edit buffer for this reason shall consist
of a single '@' character (plus the terminating <newline>), and the
<control>‐R command shall cause the editor to update the screen to
correctly represent the edit buffer.
Open and visual mode commands that set the current column set it to a
column position in the display, and not a character position in the
line. In this case, however, the column position in the display shall
be calculated for an infinite width display; for example, the column
related to a character that is part of a line that has been folded
onto additional screen lines will be offset from the display line
column where the buffer line begins, not from the beginning of a
particular display line.
The display cursor column in the display is based on the value of the
current column, as follows, with each rule applied in turn:
1. If the current column is after the last display line column used
by the displayed line, the display cursor column shall be set to
the last display line column occupied by the last non-<newline>
in the current line; otherwise, the display cursor column shall
be set to the current column.
2. If the character of which some portion is displayed in the
display line column specified by the display cursor column
requires more than a single display line column:
a. If in text input mode, the display cursor column shall be
adjusted to the first display line column in which any
portion of that character is displayed.
b. Otherwise, the display cursor column shall be adjusted to the
last display line column in which any portion of that
character is displayed.
The current column shall not be changed by these adjustments to the
display cursor column.
If an error occurs during the parsing or execution of a vi command:
* The terminal shall be alerted. Execution of the vi command shall
stop, and the cursor (for example, the current line and column)
shall not be further modified.
* Unless otherwise specified by the following command sections, it
is unspecified whether an informational message shall be
displayed.
* Any partially entered vi command shall be discarded.
* If the vi command resulted from a map expansion, all characters
from that map expansion shall be discarded, except as otherwise
specified by the map command (see ed).
* If the vi command resulted from the execution of a buffer, no
further commands caused by the execution of the buffer shall be
executed.
Page Backwards
Synopsis:
[count] <control>-B
If in open mode, the <control>‐B command shall behave identically to
the z command. Otherwise, if the current line is the first line of
the edit buffer, it shall be an error.
If the window edit option is less than 3, display a screen where the
last line of the display shall be some portion of:
(current first line) −1
otherwise, display a screen where the first line of the display shall
be some portion of:
(current first line) − count x ((window edit option) −2)
If this calculation would result in a line that is before the first
line of the edit buffer, the first line of the display shall display
some portion of the first line of the edit buffer.
Current line: If no lines from the previous display remain on the
screen, set to the last line of the display; otherwise, set to (line
− the number of new lines displayed on this screen).
Current column: Set to non-<blank>.
Scroll Forward
Synopsis:
[count] <control>-D
If the current line is the last line of the edit buffer, it shall be
an error.
If no count is specified, count shall default to the count associated
with the previous <control>‐D or <control>‐U command. If there was no
previous <control>‐D or <control>‐U command, count shall default to
the value of the scroll edit option.
If in open mode, write lines starting with the line after the current
line, until count lines or the last line of the file have been
written.
Current line: If the current line + count is past the last line of
the edit buffer, set to the last line of the edit buffer; otherwise,
set to the current line + count.
Current column: Set to non-<blank>.
Scroll Forward by Line
Synopsis:
[count] <control>-E
Display the line count lines after the last line currently displayed.
If the last line of the edit buffer is displayed, it shall be an
error. If there is no line count lines after the last line currently
displayed, the last line of the display shall display some portion of
the last line of the edit buffer.
Current line: Unchanged if the previous current character is
displayed; otherwise, set to the first line displayed.
Current column: Unchanged.
Page Forward
Synopsis:
[count] <control>-F
If in open mode, the <control>‐F command shall behave identically to
the z command. Otherwise, if the current line is the last line of the
edit buffer, it shall be an error.
If the window edit option is less than 3, display a screen where the
first line of the display shall be some portion of:
(current last line) +1
otherwise, display a screen where the first line of the display shall
be some portion of:
(current first line) + count x ((window edit option) −2)
If this calculation would result in a line that is after the last
line of the edit buffer, the last line of the display shall display
some portion of the last line of the edit buffer.
Current line: If no lines from the previous display remain on the
screen, set to the first line of the display; otherwise, set to (line
+ the number of new lines displayed on this screen).
Current column: Set to non-<blank>.
Display Information
Synopsis:
<control>-G
This command shall be equivalent to the ex file command.
Move Cursor Backwards
Synopsis:
[count] <control>-H
[count] h
the current erase character (see stty)
If there are no characters before the current character on the
current line, it shall be an error. If there are less than count
previous characters on the current line, count shall be adjusted to
the number of previous characters on the line.
If used as a motion command:
1. The text region shall be from the character before the starting
cursor up to and including the countth character before the
starting cursor.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to (column − the number of columns occupied by
count characters ending with the previous current column).
Move Down
Synopsis:
[count] <newline>
[count] <control>-J
[count] <control>-M
[count] <control>-N
[count] j
[count] <carriage-return>
[count] +
If there are less than count lines after the current line in the edit
buffer, it shall be an error.
If used as a motion command:
1. The text region shall include the starting line and the next
count − 1 lines.
2. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
Current line: Set to current line+ count.
Current column: Set to non-<blank> for the <carriage-return>,
<control>‐M, and + commands; otherwise, unchanged.
Clear and Redisplay
Synopsis:
<control>-L
If in open mode, clear the screen and redisplay the current line.
Otherwise, clear and redisplay the screen.
Current line: Unchanged.
Current column: Unchanged.
Move Up
Synopsis:
[count] <control>-P
[count] k
[count] −
If there are less than count lines before the current line in the
edit buffer, it shall be an error.
If used as a motion command:
1. The text region shall include the starting line and the previous
count lines.
2. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
Current line: Set to current line − count.
Current column: Set to non-<blank> for the − command; otherwise,
unchanged.
Redraw Screen
Synopsis:
<control>-R
If any lines have been deleted from the display screen and flagged as
deleted on the terminal using the @ convention (see the beginning of
the EXTENDED DESCRIPTION section), they shall be redisplayed to match
the contents of the edit buffer.
It is unspecified whether lines flagged with @ because they do not
fit on the terminal display shall be affected.
Current line: Unchanged.
Current column: Unchanged.
Scroll Backward
Synopsis:
[count] <control>-U
If the current line is the first line of the edit buffer, it shall be
an error.
If no count is specified, count shall default to the count associated
with the previous <control>‐D or <control>‐U command. If there was no
previous <control>‐D or <control>‐U command, count shall default to
the value of the scroll edit option.
Current line: If count is greater than the current line, set to 1;
otherwise, set to the current line − count.
Current column: Set to non-<blank>.
Scroll Backward by Line
Synopsis:
[count] <control>-Y
Display the line count lines before the first line currently
displayed.
If the current line is the first line of the edit buffer, it shall be
an error. If this calculation would result in a line that is before
the first line of the edit buffer, the first line of the display
shall display some portion of the first line of the edit buffer.
Current line: Unchanged if the previous current character is
displayed; otherwise, set to the first line displayed.
Current column: Unchanged.
Edit the Alternate File
Synopsis:
<control>-^
This command shall be equivalent to the ex edit command, with the
alternate pathname as its argument.
Terminate Command or Input Mode
Synopsis:
<ESC>
If a partial vi command (as defined by at least one, non-count
character) has been entered, discard the count and the command
character(s).
Otherwise, if no command characters have been entered, and the <ESC>
was the result of a map expansion, the terminal shall be alerted and
the <ESC> character shall be discarded, but it shall not be an error.
Otherwise, it shall be an error.
Current line: Unchanged.
Current column: Unchanged.
Search for tagstring
Synopsis:
<control>-]
If the current character is not a word or <blank>, it shall be an
error.
This command shall be equivalent to the ex tag command, with the
argument to that command defined as follows.
If the current character is a <blank>:
1. Skip all <blank> characters after the cursor up to the end of the
line.
2. If the end of the line is reached, it shall be an error.
Then, the argument to the ex tag command shall be the current
character and all subsequent characters, up to the first non-word
character or the end of the line.
Move Cursor Forward
Synopsis:
[count] <space>
[count] l (ell)
If there are less than count non-<newline> characters after the
cursor on the current line, count shall be adjusted to the number of
non-<newline> characters after the cursor on the line.
If used as a motion command:
1. If the current or countth character after the cursor is the last
non-<newline> in the line, the text region shall be comprised of
the current character up to and including the last non-<newline>
in the line. Otherwise, the text region shall be from the current
character up to, but not including, the countth character after
the cursor.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
If there are no non-<newline> characters after the current character
on the current line, it shall be an error.
Current line: Unchanged.
Current column: Set to the last column that displays any portion of
the countth character after the current character.
Replace Text with Results from Shell Command
Synopsis:
[count] ! motion shell-commands <newline>
If the motion command is the ! command repeated:
1. If the edit buffer is empty and no count was supplied, the
command shall be the equivalent of the ex :read ! command, with
the text input, and no text shall be copied to any buffer.
2. Otherwise:
a. If there are less than count −1 lines after the current line
in the edit buffer, it shall be an error.
b. The text region shall be from the current line up to and
including the next count −1 lines.
Otherwise, the text region shall be the lines in which any character
of the text region specified by the motion command appear.
Any text copied to a buffer shall be in line mode.
This command shall be equivalent to the ex ! command for the
specified lines.
Move Cursor to End-of-Line
Synopsis:
[count] $
It shall be an error if there are less than (count −1) lines after
the current line in the edit buffer.
If used as a motion command:
1. If count is 1:
a. It shall be an error if the line is empty.
b. Otherwise, the text region shall consist of all characters
from the starting cursor to the last non-<newline> in the
line, inclusive, and any text copied to a buffer shall be in
character mode.
2. Otherwise, if the starting cursor position is at or before the
first non-<blank> in the line, the text region shall consist of
the current and the next count −1 lines, and any text saved to a
buffer shall be in line mode.
3. Otherwise, the text region shall consist of all characters from
the starting cursor to the last non-<newline> in the line that is
count −1 lines forward from the current line, and any text copied
to a buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the current line + count−1.
Current column: The current column is set to the last display line
column of the last non-<newline> in the line, or column position 1 if
the line is empty.
The current column shall be adjusted to be on the last display line
column of the last non-<newline> of the current line as subsequent
commands change the current line, until a command changes the current
column.
Move to Matching Character
Synopsis:
%
If the character at the current position is not a parenthesis,
bracket, or curly brace, search forward in the line to the first one
of those characters. If no such character is found, it shall be an
error.
The matching character shall be the parenthesis, bracket, or curly
brace matching the parenthesis, bracket, or curly brace,
respectively, that was at the current position or that was found on
the current line.
Matching shall be determined as follows, for an open parenthesis:
1. Set a counter to 1.
2. Search forwards until a parenthesis is found or the end of the
edit buffer is reached.
3. If the end of the edit buffer is reached, it shall be an error.
4. If an open parenthesis is found, increment the counter by 1.
5. If a close parenthesis is found, decrement the counter by 1.
6. If the counter is zero, the current character is the matching
character.
Matching for a close parenthesis shall be equivalent, except that the
search shall be backwards, from the starting character to the
beginning of the buffer, a close parenthesis shall increment the
counter by 1, and an open parenthesis shall decrement the counter by
1.
Matching for brackets and curly braces shall be equivalent, except
that searching shall be done for open and close brackets or open and
close curly braces. It is implementation-defined whether other
characters are searched for and matched as well.
If used as a motion command:
1. If the matching cursor was after the starting cursor in the edit
buffer, and the starting cursor position was at or before the
first non-<blank> non-<newline> in the starting line, and the
matching cursor position was at or after the last non-<blank>
non-<newline> in the matching line, the text region shall consist
of the current line to the matching line, inclusive, and any text
copied to a buffer shall be in line mode.
2. If the matching cursor was before the starting cursor in the edit
buffer, and the starting cursor position was at or after the last
non-<blank> non-<newline> in the starting line, and the matching
cursor position was at or before the first non-<blank>
non-<newline> in the matching line, the text region shall consist
of the current line to the matching line, inclusive, and any text
copied to a buffer shall be in line mode.
3. Otherwise, the text region shall consist of the starting
character to the matching character, inclusive, and any text
copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the line where the matching character is
located.
Current column: Set to the last column where any portion of the
matching character is displayed.
Repeat Substitution
Synopsis:
&
Repeat the previous substitution command. This command shall be
equivalent to the ex & command with the current line as its
addresses, and without options, count, or flags.
Return to Previous Context at Beginning of Line
Synopsis:
' character
It shall be an error if there is no line in the edit buffer marked by
character.
If used as a motion command:
1. If the starting cursor is after the marked cursor, then the
locations of the starting cursor and the marked cursor in the
edit buffer shall be logically swapped.
2. The text region shall consist of the starting line up to and
including the marked line, and any text copied to a buffer shall
be in line mode.
If not used as a motion command:
Current line: Set to the line referenced by the mark.
Current column: Set to non-<blank>.
Return to Previous Context
Synopsis:
` character
It shall be an error if the marked line is no longer in the edit
buffer. If the marked line no longer contains a character in the
saved numbered character position, it shall be as if the marked
position is the first non-<blank>.
If used as a motion command:
1. It shall be an error if the marked cursor references the same
character in the edit buffer as the starting cursor.
2. If the starting cursor is after the marked cursor, then the
locations of the starting cursor and the marked cursor in the
edit buffer shall be logically swapped.
3. If the starting line is empty or the starting cursor is at or
before the first non-<blank> non-<newline> of the starting line,
and the marked cursor line is empty or the marked cursor
references the first character of the marked cursor line, the
text region shall consist of all lines containing characters from
the starting cursor to the line before the marked cursor line,
inclusive, and any text copied to a buffer shall be in line mode.
4. Otherwise, if the marked cursor line is empty or the marked
cursor references a character at or before the first non-<blank>
non-<newline> of the marked cursor line, the region of text shall
be from the starting cursor to the last non-<newline> of the line
before the marked cursor line, inclusive, and any text copied to
a buffer shall be in character mode.
5. Otherwise, the region of text shall be from the starting cursor
(inclusive), to the marked cursor (exclusive), and any text
copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the line referenced by the mark.
Current column: Set to the last column in which any portion of the
character referenced by the mark is displayed.
Return to Previous Section
Synopsis:
[count] [[
Move the cursor backward through the edit buffer to the first
character of the previous section boundary, count times.
If used as a motion command:
1. If the starting cursor was at the first character of the starting
line or the starting line was empty, and the first character of
the boundary was the first character of the boundary line, the
text region shall consist of the current line up to and including
the line where the countth next boundary starts, and any text
copied to a buffer shall be in line mode.
2. If the boundary was the last line of the edit buffer or the last
non-<newline> of the last line of the edit buffer, the text
region shall consist of the last character in the edit buffer up
to and including the starting character, and any text saved to a
buffer shall be in character mode.
3. Otherwise, the text region shall consist of the starting
character up to but not including the first character in the
countth next boundary, and any text copied to a buffer shall be
in character mode.
If not used as a motion command:
Current line: Set to the line where the countth next boundary in the
edit buffer starts.
Current column: Set to the last column in which any portion of the
first character of the countth next boundary is displayed, or column
position 1 if the line is empty.
Move to Next Section
Synopsis:
[count] ]]
Move the cursor forward through the edit buffer to the first
character of the next section boundary, count times.
If used as a motion command:
1. If the starting cursor was at the first character of the starting
line or the starting line was empty, and the first character of
the boundary was the first character of the boundary line, the
text region shall consist of the current line up to and including
the line where the countth previous boundary starts, and any text
copied to a buffer shall be in line mode.
2. If the boundary was the first line of the edit buffer, the text
region shall consist of the first character in the edit buffer up
to but not including the starting character, and any text copied
to a buffer shall be in character mode.
3. Otherwise, the text region shall consist of the first character
in the countth previous section boundary up to but not including
the starting character, and any text copied to a buffer shall be
in character mode.
If not used as a motion command:
Current line: Set to the line where the countth previous boundary in
the edit buffer starts.
Current column: Set to the last column in which any portion of the
first character of the countth previous boundary is displayed, or
column position 1 if the line is empty.
Move to First Non-<blank> Position on Current Line
Synopsis:
^
If used as a motion command:
1. If the line has no non-<blank> non-<newline> characters, or if
the cursor is at the first non-<blank> non-<newline> of the line,
it shall be an error.
2. If the cursor is before the first non-<blank> non-<newline> of
the line, the text region shall be comprised of the current
character, up to, but not including, the first non-<blank>
non-<newline> of the line.
3. If the cursor is after the first non-<blank> non-<newline> of the
line, the text region shall be from the character before the
starting cursor up to and including the first non-<blank>
non-<newline> of the line.
4. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to non-<blank>.
Current and Line Above
Synopsis:
[count] _
If there are less than count −1 lines after the current line in the
edit buffer, it shall be an error.
If used as a motion command:
1. If count is less than 2, the text region shall be the current
line.
2. Otherwise, the text region shall include the starting line and
the next count −1 lines.
3. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
Current line: Set to current line + count −1.
Current column: Set to non-<blank>.
Move Back to Beginning of Sentence
Synopsis:
[count] (
Move backward to the beginning of a sentence. This command shall be
equivalent to the [[ command, with the exception that sentence
boundaries shall be used instead of section boundaries.
Move Forward to Beginning of Sentence
Synopsis:
[count] )
Move forward to the beginning of a sentence. This command shall be
equivalent to the ]] command, with the exception that sentence
boundaries shall be used instead of section boundaries.
Move Back to Preceding Paragraph
Synopsis:
[count] {
Move back to the beginning of the preceding paragraph. This command
shall be equivalent to the [[ command, with the exception that
paragraph boundaries shall be used instead of section boundaries.
Move Forward to Next Paragraph
Synopsis:
[count] }
Move forward to the beginning of the next paragraph. This command
shall be equivalent to the ]] command, with the exception that
paragraph boundaries shall be used instead of section boundaries.
Move to Specific Column Position
Synopsis:
[count] |
For the purposes of this command, lines that are too long for the
current display and that have been folded shall be treated as having
a single, 1−based, number of columns.
If there are less than count columns in which characters from the
current line are displayed on the screen, count shall be adjusted to
be the last column in which any portion of the line is displayed on
the screen.
If used as a motion command:
1. If the line is empty, or the cursor character is the same as the
character on the countth column of the line, it shall be an
error.
2. If the cursor is before the countth column of the line, the text
region shall be comprised of the current character, up to but not
including the character on the countth column of the line.
3. If the cursor is after the countth column of the line, the text
region shall be from the character before the starting cursor up
to and including the character on the countth column of the line.
4. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of the
character that is displayed in the count column of the line is
displayed.
Reverse Find Character
Synopsis:
[count] ,
If the last F, f, T, or t command was F, f, T, or t, this command
shall be equivalent to an f, F, t, or T command, respectively, with
the specified count and the same search character.
If there was no previous F, f, T, or t command, it shall be an error.
Repeat
Synopsis:
[count] .
Repeat the last !, <, >, A, C, D, I, J, O, P, R, S, X, Y, a, c, d, i,
o, p, r, s, x, y, or ~ command. It shall be an error if none of these
commands have been executed. Commands (other than commands that enter
text input mode) executed as a result of map expansions, shall not
change the value of the last repeatable command.
Repeated commands with associated motion commands shall repeat the
motion command as well; however, any specified count shall replace
the count(s) that were originally specified to the repeated command
or its associated motion command.
If the motion component of the repeated command is f, F, t, or T, the
repeated command shall not set the remembered search character for
the ; and , commands.
If the repeated command is p or P, and the buffer associated with
that command was a numeric buffer named with a number less than 9,
the buffer associated with the repeated command shall be set to be
the buffer named by the name of the previous buffer logically
incremented by 1.
If the repeated character is a text input command, the input text
associated with that command is repeated literally:
* Input characters are neither macro or abbreviation-expanded.
* Input characters are not interpreted in any special way with the
exception that <newline>, <carriage-return>, and <control>‐T
behave as described in Input Mode Commands in vi.
Current line: Set as described for the repeated command.
Current column: Set as described for the repeated command.
Find Regular Expression
Synopsis:
/
If the input line contains no non-<newline> characters, it shall be
equivalent to a line containing only the last regular expression
encountered. The enhanced regular expressions supported by vi are
described in Regular Expressions in ex.
Otherwise, the line shall be interpreted as one or more regular
expressions, optionally followed by an address offset or a vi z
command.
If the regular expression is not the last regular expression on the
line, or if a line offset or z command is specified, the regular
expression shall be terminated by an unescaped '/' character, which
shall not be used as part of the regular expression. If the regular
expression is not the first regular expression on the line, it shall
be preceded by zero or more <blank> characters, a <semicolon>, zero
or more <blank> characters, and a leading '/' character, which shall
not be interpreted as part of the regular expression. It shall be an
error to precede any regular expression with any characters other
than these.
Each search shall begin from the character after the first character
of the last match (or, if it is the first search, after the cursor).
If the wrapscan edit option is set, the search shall continue to the
character before the starting cursor character; otherwise, to the end
of the edit buffer. It shall be an error if any search fails to find
a match, and an informational message to this effect shall be
displayed.
An optional address offset (see Addressing in ex) can be specified
after the last regular expression by including a trailing '/'
character after the regular expression and specifying the address
offset. This offset will be from the line containing the match for
the last regular expression specified. It shall be an error if the
line offset would indicate a line address less than 1 or greater than
the last line in the edit buffer. An address offset of zero shall be
supported. It shall be an error to follow the address offset with any
other characters than <blank> characters.
If not used as a motion command, an optional z command (see Redraw
Window) can be specified after the last regular expression by
including a trailing '/' character after the regular expression, zero
or more <blank> characters, a 'z', zero or more <blank> characters,
an optional new window edit option value, zero or more <blank>
characters, and a location character. The effect shall be as if the z
command was executed after the / command. It shall be an error to
follow the z command with any other characters than <blank>
characters.
The remembered search direction shall be set to forward.
If used as a motion command:
1. It shall be an error if the last match references the same
character in the edit buffer as the starting cursor.
2. If any address offset is specified, the last match shall be
adjusted by the specified offset as described previously.
3. If the starting cursor is after the last match, then the
locations of the starting cursor and the last match in the edit
buffer shall be logically swapped.
4. If any address offset is specified, the text region shall consist
of all lines containing characters from the starting cursor to
the last match line, inclusive, and any text copied to a buffer
shall be in line mode.
5. Otherwise, if the starting line is empty or the starting cursor
is at or before the first non-<blank> non-<newline> of the
starting line, and the last match line is empty or the last match
starts at the first character of the last match line, the text
region shall consist of all lines containing characters from the
starting cursor to the line before the last match line,
inclusive, and any text copied to a buffer shall be in line mode.
6. Otherwise, if the last match line is empty or the last match
begins at a character at or before the first non-<blank>
non-<newline> of the last match line, the region of text shall be
from the current cursor to the last non-<newline> of the line
before the last match line, inclusive, and any text copied to a
buffer shall be in character mode.
7. Otherwise, the region of text shall be from the current cursor
(inclusive), to the first character of the last match
(exclusive), and any text copied to a buffer shall be in
character mode.
If not used as a motion command:
Current line: If a match is found, set to the last matched line plus
the address offset, if any; otherwise, unchanged.
Current column: Set to the last column on which any portion of the
first character in the last matched string is displayed, if a match
is found; otherwise, unchanged.
Move to First Character in Line
Synopsis:
0 (zero)
Move to the first character on the current line. The character '0'
shall not be interpreted as a command if it is immediately preceded
by a digit.
If used as a motion command:
1. If the cursor character is the first character in the line, it
shall be an error.
2. The text region shall be from the character before the cursor
character up to and including the first character in the line.
3. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: The last column in which any portion of the first
character in the line is displayed, or if the line is empty,
unchanged.
Execute an ex Command
Synopsis:
:
Execute one or more ex commands.
If any portion of the screen other than the last line of the screen
was overwritten by any ex command (except shell), vi shall display a
message indicating that it is waiting for an input from the user, and
shall then read a character. This action may also be taken for other,
unspecified reasons.
If the next character entered is a ':', another ex command shall be
accepted and executed. Any other character shall cause the screen to
be refreshed and vi shall return to command mode.
Current line: As specified for the ex command.
Current column: As specified for the ex command.
Repeat Find
Synopsis:
[count] ;
This command shall be equivalent to the last F, f, T, or t command,
with the specified count, and with the same search character used for
the last F, f, T, or t command. If there was no previous F, f, T, or
t command, it shall be an error.
Shift Left
Synopsis:
[count] < motion
If the motion command is the < command repeated:
1. If there are less than count −1 lines after the current line in
the edit buffer, it shall be an error.
2. The text region shall be from the current line, up to and
including the next count −1 lines.
Shift any line in the text region specified by the count and motion
command one shiftwidth (see the ex shiftwidth option) toward the
start of the line, as described by the ex < command. The unshifted
lines shall be copied to the unnamed buffer in line mode.
Current line: If the motion was from the current cursor position
toward the end of the edit buffer, unchanged. Otherwise, set to the
first line in the edit buffer that is part of the text region
specified by the motion command.
Current column: Set to non-<blank>.
Shift Right
Synopsis:
[count] > motion
If the motion command is the > command repeated:
1. If there are less than count −1 lines after the current line in
the edit buffer, it shall be an error.
2. The text region shall be from the current line, up to and
including the next count −1 lines.
Shift any line with characters in the text region specified by the
count and motion command one shiftwidth (see the ex shiftwidth
option) away from the start of the line, as described by the ex >
command. The unshifted lines shall be copied into the unnamed buffer
in line mode.
Current line: If the motion was from the current cursor position
toward the end of the edit buffer, unchanged. Otherwise, set to the
first line in the edit buffer that is part of the text region
specified by the motion command.
Current column: Set to non-<blank>.
Scan Backwards for Regular Expression
Synopsis:
?
Scan backwards; the ? command shall be equivalent to the / command
(see Find Regular Expression) with the following exceptions:
1. The input prompt shall be a '?'.
2. Each search shall begin from the character before the first
character of the last match (or, if it is the first search, the
character before the cursor character).
3. The search direction shall be from the cursor toward the
beginning of the edit buffer, and the wrapscan edit option shall
affect whether the search wraps to the end of the edit buffer and
continues.
4. The remembered search direction shall be set to backward.
Execute
Synopsis:
@buffer
If the buffer is specified as @, the last buffer executed shall be
used. If no previous buffer has been executed, it shall be an error.
Behave as if the contents of the named buffer were entered as
standard input. After each line of a line-mode buffer, and all but
the last line of a character mode buffer, behave as if a <newline>
were entered as standard input.
If an error occurs during this process, an error message shall be
written, and no more characters resulting from the execution of this
command shall be processed.
If a count is specified, behave as if that count were entered as user
input before the characters from the @ buffer were entered.
Current line: As specified for the individual commands.
Current column: As specified for the individual commands.
Reverse Case
Synopsis:
[count] ~
Reverse the case of the current character and the next count −1
characters, such that lowercase characters that have uppercase
counterparts shall be changed to uppercase characters, and uppercase
characters that have lowercase counterparts shall be changed to
lowercase characters, as prescribed by the current locale. No other
characters shall be affected by this command.
If there are less than count −1 characters after the cursor in the
edit buffer, count shall be adjusted to the number of characters
after the cursor in the edit buffer minus 1.
For the purposes of this command, the next character after the last
non-<newline> on the line shall be the next character in the edit
buffer.
Current line: Set to the line including the (count−1)th character
after the cursor.
Current column: Set to the last column in which any portion of the
(count−1)th character after the cursor is displayed.
Append
Synopsis:
[count] a
Enter text input mode after the current cursor position. No
characters already in the edit buffer shall be affected by this
command. A count shall cause the input text to be appended count −1
more times to the end of the input.
Current line/column: As specified for the text input commands (see
Input Mode Commands in vi).
Append at End-of-Line
Synopsis:
[count] A
This command shall be equivalent to the vi command:
$ [ count ] a
(see Append).
Move Backward to Preceding Word
Synopsis:
[count] b
With the exception that words are used as the delimiter instead of
bigwords, this command shall be equivalent to the B command.
Move Backward to Preceding Bigword
Synopsis:
[count] B
If the edit buffer is empty or the cursor is on the first character
of the edit buffer, it shall be an error. If less than count bigwords
begin between the cursor and the start of the edit buffer, count
shall be adjusted to the number of bigword beginnings between the
cursor and the start of the edit buffer.
If used as a motion command:
1. The text region shall be from the first character of the countth
previous bigword beginning up to but not including the cursor
character.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the line containing the current column.
Current column: Set to the last column upon which any part of the
first character of the countth previous bigword is displayed.
Change
Synopsis:
[buffer][count] c motion
If the motion command is the c command repeated:
1. The buffer text shall be in line mode.
2. If there are less than count −1 lines after the current line in
the edit buffer, it shall be an error.
3. The text region shall be from the current line up to and
including the next count −1 lines.
Otherwise, the buffer text mode and text region shall be as specified
by the motion command.
The replaced text shall be copied into buffer, if specified, and into
the unnamed buffer. If the text to be replaced contains characters
from more than a single line, or the buffer text is in line mode, the
replaced text shall be copied into the numeric buffers as well.
If the buffer text is in line mode:
1. Any lines that contain characters in the region shall be deleted,
and the editor shall enter text input mode at the beginning of a
new line which shall replace the first line deleted.
2. If the autoindent edit option is set, autoindent characters equal
to the autoindent characters on the first line deleted shall be
inserted as if entered by the user.
Otherwise, if characters from more than one line are in the region of
text:
1. The text shall be deleted.
2. Any text remaining in the last line in the text region shall be
appended to the first line in the region, and the last line in
the region shall be deleted.
3. The editor shall enter text input mode after the last character
not deleted from the first line in the text region, if any;
otherwise, on the first column of the first line in the region.
Otherwise:
1. If the glyph for '$' is smaller than the region, the end of the
region shall be marked with a '$'.
2. The editor shall enter text input mode, overwriting the region of
text.
Current line/column: As specified for the text input commands (see
Input Mode Commands in vi).
Change to End-of-Line
Synopsis:
[buffer][count] C
This command shall be equivalent to the vi command:
[buffer][count] c$
See the c command.
Delete
Synopsis:
[buffer][count] d motion
If the motion command is the d command repeated:
1. The buffer text shall be in line mode.
2. If there are less than count −1 lines after the current line in
the edit buffer, it shall be an error.
3. The text region shall be from the current line up to and
including the next count −1 lines.
Otherwise, the buffer text mode and text region shall be as specified
by the motion command.
If in open mode, and the current line is deleted, and the line
remains on the display, an '@' character shall be displayed as the
first glyph of that line.
Delete the region of text into buffer, if specified, and into the
unnamed buffer. If the text to be deleted contains characters from
more than a single line, or the buffer text is in line mode, the
deleted text shall be copied into the numeric buffers, as well.
Current line: Set to the first text region line that appears in the
edit buffer, unless that line has been deleted, in which case it
shall be set to the last line in the edit buffer, or line 1 if the
edit buffer is empty.
Current column:
1. If the line is empty, set to column position 1.
2. Otherwise, if the buffer text is in line mode or the motion was
from the cursor toward the end of the edit buffer:
a. If a character from the current line is displayed in the
current column, set to the last column that displays any
portion of that character.
b. Otherwise, set to the last column in which any portion of any
character in the line is displayed.
3. Otherwise, if a character is displayed in the column that began
the text region, set to the last column that displays any portion
of that character.
4. Otherwise, set to the last column in which any portion of any
character in the line is displayed.
Delete to End-of-Line
Synopsis:
[buffer] D
Delete the text from the current position to the end of the current
line; equivalent to the vi command:
[buffer] d$
Move to End-of-Word
Synopsis:
[count] e
With the exception that words are used instead of bigwords as the
delimiter, this command shall be equivalent to the E command.
Move to End-of-Bigword
Synopsis:
[count] E
If the edit buffer is empty it shall be an error. If less than count
bigwords end between the cursor and the end of the edit buffer, count
shall be adjusted to the number of bigword endings between the cursor
and the end of the edit buffer.
If used as a motion command:
1. The text region shall be from the last character of the countth
next bigword up to and including the cursor character.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the line containing the current column.
Current column: Set to the last column upon which any part of the
last character of the countth next bigword is displayed.
Find Character in Current Line (Forward)
Synopsis:
[count] f character
It shall be an error if count occurrences of the character do not
occur after the cursor in the line.
If used as a motion command:
1. The text range shall be from the cursor character up to and
including the countth occurrence of the specified character after
the cursor.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of the
countth occurrence of the specified character after the cursor
appears in the line.
Find Character in Current Line (Reverse)
Synopsis:
[count] F character
It shall be an error if count occurrences of the character do not
occur before the cursor in the line.
If used as a motion command:
1. The text region shall be from the countth occurrence of the
specified character before the cursor, up to, but not including
the cursor character.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of the
countth occurrence of the specified character before the cursor
appears in the line.
Move to Line
Synopsis:
[count] G
If count is not specified, it shall default to the last line of the
edit buffer. If count is greater than the last line of the edit
buffer, it shall be an error.
If used as a motion command:
1. The text region shall be from the cursor line up to and including
the specified line.
2. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
Current line: Set to count if count is specified; otherwise, the last
line.
Current column: Set to non-<blank>.
Move to Top of Screen
Synopsis:
[count] H
If the beginning of the line count greater than the first line of
which any portion appears on the display does not exist, it shall be
an error.
If used as a motion command:
1. If in open mode, the text region shall be the current line.
2. Otherwise, the text region shall be from the starting line up to
and including (the first line of the display + count −1).
3. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
If in open mode, this command shall set the current column to
non-<blank> and do nothing else.
Otherwise, it shall set the current line and current column as
follows.
Current line: Set to (the first line of the display + count −1).
Current column: Set to non-<blank>.
Insert Before Cursor
Synopsis:
[count] i
Enter text input mode before the current cursor position. No
characters already in the edit buffer shall be affected by this
command. A count shall cause the input text to be appended count −1
more times to the end of the input.
Current line/column: As specified for the text input commands (see
Input Mode Commands in vi).
Insert at Beginning of Line
Synopsis:
[count] I
This command shall be equivalent to the vi command ^[count]i.
Join
Synopsis:
[count] J
If the current line is the last line in the edit buffer, it shall be
an error.
This command shall be equivalent to the ex join command with no
addresses, and an ex command count value of 1 if count was not
specified or if a count of 1 was specified, and an ex command count
value of count −1 for any other value of count, except that the
current line and column shall be set as follows.
Current line: Unchanged.
Current column: The last column in which any portion of the character
following the last character in the initial line is displayed, or the
last non-<newline> in the line if no characters were appended.
Move to Bottom of Screen
Synopsis:
[count] L
If the beginning of the line count less than the last line of which
any portion appears on the display does not exist, it shall be an
error.
If used as a motion command:
1. If in open mode, the text region shall be the current line.
2. Otherwise, the text region shall include all lines from the
starting cursor line to (the last line of the display −(count
−1)).
3. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
1. If in open mode, this command shall set the current column to
non-<blank> and do nothing else.
2. Otherwise, it shall set the current line and current column as
follows.
Current line: Set to (the last line of the display −(count −1)).
Current column: Set to non-<blank>.
Mark Position
Synopsis:
m letter
This command shall be equivalent to the ex mark command with the
specified character as an argument.
Move to Middle of Screen
Synopsis:
M
The middle line of the display shall be calculated as follows:
(the top line of the display) + (((number of lines displayed) +1) /2) −1
If used as a motion command:
1. If in open mode, the text region shall be the current line.
2. Otherwise, the text region shall include all lines from the
starting cursor line up to and including the middle line of the
display.
3. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
If in open mode, this command shall set the current column to
non-<blank> and do nothing else.
Otherwise, it shall set the current line and current column as
follows.
Current line: Set to the middle line of the display.
Current column: Set to non-<blank>.
Repeat Regular Expression Find (Forward)
Synopsis:
n
If the remembered search direction was forward, the n command shall
be equivalent to the vi / command with no characters entered by the
user. Otherwise, it shall be equivalent to the vi ? command with no
characters entered by the user.
If the n command is used as a motion command for the ! command, the
editor shall not enter text input mode on the last line on the
screen, and shall behave as if the user entered a single '!'
character as the text input.
Repeat Regular Expression Find (Reverse)
Synopsis:
N
Scan for the next match of the last pattern given to / or ?, but in
the reverse direction; this is the reverse of n.
If the remembered search direction was forward, the N command shall
be equivalent to the vi ? command with no characters entered by the
user. Otherwise, it shall be equivalent to the vi / command with no
characters entered by the user. If the N command is used as a motion
command for the ! command, the editor shall not enter text input
mode on the last line on the screen, and shall behave as if the user
entered a single ! character as the text input.
Insert Empty Line Below
Synopsis:
o
Enter text input mode in a new line appended after the current line.
A count shall cause the input text to be appended count −1 more times
to the end of the already added text, each time starting on a new,
appended line.
Current line/column: As specified for the text input commands (see
Input Mode Commands in vi).
Insert Empty Line Above
Synopsis:
O
Enter text input mode in a new line inserted before the current line.
A count shall cause the input text to be appended count −1 more times
to the end of the already added text, each time starting on a new,
appended line.
Current line/column: As specified for the text input commands (see
Input Mode Commands in vi).
Put from Buffer Following
Synopsis:
[buffer] p
If no buffer is specified, the unnamed buffer shall be used.
If the buffer text is in line mode, the text shall be appended below
the current line, and each line of the buffer shall become a new line
in the edit buffer. A count shall cause the buffer text to be
appended count −1 more times to the end of the already added text,
each time starting on a new, appended line.
If the buffer text is in character mode, the text shall be appended
into the current line after the cursor, and each line of the buffer
other than the first and last shall become a new line in the edit
buffer. A count shall cause the buffer text to be appended count −1
more times to the end of the already added text, each time starting
after the last added character.
Current line: If the buffer text is in line mode, set the line to
line +1; otherwise, unchanged.
Current column: If the buffer text is in line mode:
1. If there is a non-<blank> in the first line of the buffer, set to
the last column on which any portion of the first non-<blank> in
the line is displayed.
2. If there is no non-<blank> in the first line of the buffer, set
to the last column on which any portion of the last non-<newline>
in the first line of the buffer is displayed.
If the buffer text is in character mode:
1. If the text in the buffer is from more than a single line, then
set to the last column on which any portion of the first
character from the buffer is displayed.
2. Otherwise, if the buffer is the unnamed buffer, set to the last
column on which any portion of the last character from the buffer
is displayed.
3. Otherwise, set to the first column on which any portion of the
first character from the buffer is displayed.
Put from Buffer Before
Synopsis:
[buffer] P
If no buffer is specified, the unnamed buffer shall be used.
If the buffer text is in line mode, the text shall be inserted above
the current line, and each line of the buffer shall become a new line
in the edit buffer. A count shall cause the buffer text to be
appended count −1 more times to the end of the already added text,
each time starting on a new, appended line.
If the buffer text is in character mode, the text shall be inserted
into the current line before the cursor, and each line of the buffer
other than the first and last shall become a new line in the edit
buffer. A count shall cause the buffer text to be appended count −1
more times to the end of the already added text, each time starting
after the last added character.
Current line: Unchanged.
Current column: If the buffer text is in line mode:
1. If there is a non-<blank> in the first line of the buffer, set to
the last column on which any portion of that character is
displayed.
2. If there is no non-<blank> in the first line of the buffer, set
to the last column on which any portion of the last non-<newline>
in the first line of the buffer is displayed.
If the buffer text is in character mode:
1. If the text in the buffer is from more than a single line, then
set to the last column on which any portion of the first
character from the buffer is displayed.
2. Otherwise, if the buffer is the unnamed buffer, set to the last
column on which any portion of the last character from the buffer
is displayed.
3. Otherwise, set to the first column on which any portion of the
first character from the buffer is displayed.
Enter ex Mode
Synopsis:
Q
Leave visual or open mode and enter ex command mode.
Current line: Unchanged.
Current column: Unchanged.
Replace Character
Synopsis:
[count] r character
Replace the count characters at and after the cursor with the
specified character. If there are less than count non-<newline>
characters at and after the cursor on the line, it shall be an error.
If character is <control>‐V, any next character other than the
<newline> shall be stripped of any special meaning and used as a
literal character.
If character is <ESC>, no replacement shall be made and the current
line and current column shall be unchanged.
If character is <carriage-return> or <newline>, count new lines shall
be appended to the current line. All but the last of these lines
shall be empty. count characters at and after the cursor shall be
discarded, and any remaining characters after the cursor in the
current line shall be moved to the last of the new lines. If the
autoindent edit option is set, they shall be preceded by the same
number of autoindent characters found on the line from which the
command was executed.
Current line: Unchanged unless the replacement character is a
<carriage-return> or <newline>, in which case it shall be set to line
+ count.
Current column: Set to the last column position on which a portion of
the last replaced character is displayed, or if the replacement
character caused new lines to be created, set to non-<blank>.
Replace Characters
Synopsis:
R
Enter text input mode at the current cursor position possibly
replacing text on the current line. A count shall cause the input
text to be appended count −1 more times to the end of the input.
Current line/column: As specified for the text input commands (see
Input Mode Commands in vi).
Substitute Character
Synopsis:
[buffer][count] s
This command shall be equivalent to the vi command:
[buffer][count] c<space>
Substitute Lines
Synopsis:
[buffer][count] S
This command shall be equivalent to the vi command:
[buffer][count] c_
Move Cursor to Before Character (Forward)
Synopsis:
[count] t character
It shall be an error if count occurrences of the character do not
occur after the cursor in the line.
If used as a motion command:
1. The text region shall be from the cursor up to but not including
the countth occurrence of the specified character after the
cursor.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of the
character before the countth occurrence of the specified character
after the cursor appears in the line.
Move Cursor to After Character (Reverse)
Synopsis:
[count] T character
It shall be an error if count occurrences of the character do not
occur before the cursor in the line.
If used as a motion command:
1. If the character before the cursor is the specified character, it
shall be an error.
2. The text region shall be from the character before the cursor up
to but not including the countth occurrence of the specified
character before the cursor.
3. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of the
character after the countth occurrence of the specified character
before the cursor appears in the line.
Undo
Synopsis:
u
This command shall be equivalent to the ex undo command except that
the current line and current column shall be set as follows:
Current line: Set to the first line added or changed if any;
otherwise, move to the line preceding any deleted text if one exists;
otherwise, move to line 1.
Current column: If undoing an ex command, set to the first
non-<blank>.
Otherwise, if undoing a text input command:
1. If the command was a C, c, O, o, R, S, or s command, the current
column shall be set to the value it held when the text input
command was entered.
2. Otherwise, set to the last column in which any portion of the
first character after the deleted text is displayed, or, if no
non-<newline> characters follow the text deleted from this line,
set to the last column in which any portion of the last
non-<newline> in the line is displayed, or 1 if the line is
empty.
Otherwise, if a single line was modified (that is, not added or
deleted) by the u command:
1. If text was added or changed, set to the last column in which any
portion of the first character added or changed is displayed.
2. If text was deleted, set to the last column in which any portion
of the first character after the deleted text is displayed, or,
if no non-<newline> characters follow the deleted text, set to
the last column in which any portion of the last non-<newline> in
the line is displayed, or 1 if the line is empty.
Otherwise, set to non-<blank>.
Undo Current Line
Synopsis:
U
Restore the current line to its state immediately before the most
recent time that it became the current line.
Current line: Unchanged.
Current column: Set to the first column in the line in which any
portion of the first character in the line is displayed.
Move to Beginning of Word
Synopsis:
[count] w
With the exception that words are used as the delimiter instead of
bigwords, this command shall be equivalent to the W command.
Move to Beginning of Bigword
Synopsis:
[count] W
If the edit buffer is empty, it shall be an error. If there are less
than count bigwords between the cursor and the end of the edit
buffer, count shall be adjusted to move the cursor to the last
bigword in the edit buffer.
If used as a motion command:
1. If the associated command is c, count is 1, and the cursor is on
a <blank>, the region of text shall be the current character and
no further action shall be taken.
2. If there are less than count bigwords between the cursor and the
end of the edit buffer, then the command shall succeed, and the
region of text shall include the last character of the edit
buffer.
3. If there are <blank> characters or an end-of-line that precede
the countth bigword, and the associated command is c, the region
of text shall be up to and including the last character before
the preceding <blank> characters or end-of-line.
4. If there are <blank> characters or an end-of-line that precede
the bigword, and the associated command is d or y, the region of
text shall be up to and including the last <blank> before the
start of the bigword or end-of-line.
5. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
1. If the cursor is on the last character of the edit buffer, it
shall be an error.
Current line: Set to the line containing the current column.
Current column: Set to the last column in which any part of the first
character of the countth next bigword is displayed.
Delete Character at Cursor
Synopsis:
[buffer][count] x
Delete the count characters at and after the current character into
buffer, if specified, and into the unnamed buffer.
If the line is empty, it shall be an error. If there are less than
count non-<newline> characters at and after the cursor on the current
line, count shall be adjusted to the number of non-<newline>
characters at and after the cursor.
Current line: Unchanged.
Current column: If the line is empty, set to column position 1.
Otherwise, if there were count or less non-<newline> characters at
and after the cursor on the current line, set to the last column that
displays any part of the last non-<newline> of the line. Otherwise,
unchanged.
Delete Character Before Cursor
Synopsis:
[buffer][count] X
Delete the count characters before the current character into buffer,
if specified, and into the unnamed buffer.
If there are no characters before the current character on the
current line, it shall be an error. If there are less than count
previous characters on the current line, count shall be adjusted to
the number of previous characters on the line.
Current line: Unchanged.
Current column: Set to (current column − the width of the deleted
characters).
Yank
Synopsis:
[buffer][count] y motion
Copy (yank) the region of text into buffer, if specified, and into
the unnamed buffer.
If the motion command is the y command repeated:
1. The buffer shall be in line mode.
2. If there are less than count −1 lines after the current line in
the edit buffer, it shall be an error.
3. The text region shall be from the current line up to and
including the next count −1 lines.
Otherwise, the buffer text mode and text region shall be as specified
by the motion command.
Current line: If the motion was from the current cursor position
toward the end of the edit buffer, unchanged. Otherwise, set to the
first line in the edit buffer that is part of the text region
specified by the motion command.
Current column:
1. If the motion was from the current cursor position toward the end
of the edit buffer, unchanged.
2. Otherwise, if the current line is empty, set to column position
1.
3. Otherwise, set to the last column that displays any part of the
first character in the file that is part of the text region
specified by the motion command.
Yank Current Line
Synopsis:
[buffer][count] Y
This command shall be equivalent to the vi command:
[buffer][count] y_
Redraw Window
If in open mode, the z command shall have the Synopsis:
Synopsis:
[count] z
If count is not specified, it shall default to the window edit option
−1. The z command shall be equivalent to the ex z command, with a
type character of = and a count of count −2, except that the current
line and current column shall be set as follows, and the window edit
option shall not be affected. If the calculation for the count
argument would result in a negative number, the count argument to the
ex z command shall be zero. A blank line shall be written after the
last line is written.
Current line: Unchanged.
Current column: Unchanged.
If not in open mode, the z command shall have the following Synopsis:
Synopsis:
[line] z [count] character
If line is not specified, it shall default to the current line. If
line is specified, but is greater than the number of lines in the
edit buffer, it shall default to the number of lines in the edit
buffer.
If count is specified, the value of the window edit option shall be
set to count (as described in the ex window command), and the screen
shall be redrawn.
line shall be placed as specified by the following characters:
<newline>, <carriage-return>
Place the beginning of the line on the first line of the
display.
. Place the beginning of the line in the center of the display.
The middle line of the display shall be calculated as described
for the M command.
− Place an unspecified portion of the line on the last line of
the display.
+ If line was specified, equivalent to the <newline> case. If
line was not specified, display a screen where the first line
of the display shall be (current last line) +1. If there are no
lines after the last line in the display, it shall be an error.
^ If line was specified, display a screen where the last line of
the display shall contain an unspecified portion of the first
line of a display that had an unspecified portion of the
specified line on the last line of the display. If this
calculation results in a line before the beginning of the edit
buffer, display the first screen of the edit buffer.
Otherwise, display a screen where the last line of the display
shall contain an unspecified portion of (current first line
−1). If this calculation results in a line before the beginning
of the edit buffer, it shall be an error.
Current line: If line and the '^' character were specified:
1. If the first screen was displayed as a result of the command
attempting to display lines before the beginning of the edit
buffer: if the first screen was already displayed, unchanged;
otherwise, set to (current first line −1).
2. Otherwise, set to the last line of the display.
If line and the '+' character were specified, set to the first line
of the display.
Otherwise, if line was specified, set to line.
Otherwise, unchanged.
Current column: Set to non-<blank>.
Exit
Synopsis:
ZZ
This command shall be equivalent to the ex xit command with no
addresses, trailing !, or filename (see the ex xit command).
Input Mode Commands in vi
In text input mode, the current line shall consist of zero or more of
the following categories, plus the terminating <newline>:
1. Characters preceding the text input entry point
Characters in this category shall not be modified during text
input mode.
2. autoindent characters
autoindent characters shall be automatically inserted into each
line that is created in text input mode, either as a result of
entering a <newline> or <carriage-return> while in text input
mode, or as an effect of the command itself; for example, O or o
(see the ex autoindent command), as if entered by the user.
It shall be possible to erase autoindent characters with the
<control>‐D command; it is unspecified whether they can be erased
by <control>‐H, <control>‐U, and <control>‐W characters. Erasing
any autoindent character turns the glyph into erase-columns and
deletes the character from the edit buffer, but does not change
its representation on the screen.
3. Text input characters
Text input characters are the characters entered by the user.
Erasing any text input character turns the glyph into erase-
columns and deletes the character from the edit buffer, but does
not change its representation on the screen.
Each text input character entered by the user (that does not have
a special meaning) shall be treated as follows:
a. The text input character shall be appended to the last
character in the edit buffer from the first, second, or third
categories.
b. If there are no erase-columns on the screen, the text input
command was the R command, and characters in the fifth
category from the original line follow the cursor, the next
such character shall be deleted from the edit buffer. If the
slowopen edit option is not set, the corresponding glyph on
the screen shall become erase-columns.
c. If there are erase-columns on the screen, as many columns as
they occupy, or as are necessary, shall be overwritten to
display the text input character. (If only part of a multi-
column glyph is overwritten, the remainder shall be left on
the screen, and continue to be treated as erase-columns; it
is unspecified whether the remainder of the glyph is modified
in any way.)
d. If additional display line columns are needed to display the
text input character:
i. If the slowopen edit option is set, the text input
characters shall be displayed on subsequent display line
columns, overwriting any characters displayed in those
columns.
ii. Otherwise, any characters currently displayed on or
after the column on the display line where the text
input character is to be displayed shall be pushed ahead
the number of display line columns necessary to display
the rest of the text input character.
4. Erase-columns
Erase-columns are not logically part of the edit buffer,
appearing only on the screen, and may be overwritten on the
screen by subsequent text input characters. When text input mode
ends, all erase-columns shall no longer appear on the screen.
Erase-columns are initially the region of text specified by the c
command (see Change); however, erasing autoindent or text input
characters causes the glyphs of the erased characters to be
treated as erase-columns.
5. Characters following the text region for the c command, or the
text input entry point for all other commands
Characters in this category shall not be modified during text
input mode, except as specified in category 3.b. for the R text
input command, or as <blank> characters deleted when a <newline>
or <carriage-return> is entered.
It is unspecified whether it is an error to attempt to erase past the
beginning of a line that was created by the entry of a <newline> or
<carriage-return> during text input mode. If it is not an error, the
editor shall behave as if the erasing character was entered
immediately after the last text input character entered on the
previous line, and all of the non-<newline> characters on the current
line shall be treated as erase-columns.
When text input mode is entered, or after a text input mode character
is entered (except as specified for the special characters below),
the cursor shall be positioned as follows:
1. On the first column that displays any part of the first erase-
column, if one exists
2. Otherwise, if the slowopen edit option is set, on the first
display line column after the last character in the first,
second, or third categories, if one exists
3. Otherwise, the first column that displays any part of the first
character in the fifth category, if one exists
4. Otherwise, the display line column after the last character in
the first, second, or third categories, if one exists
5. Otherwise, on column position 1
The characters that are updated on the screen during text input mode
are unspecified, other than that the last text input character shall
always be updated, and, if the slowopen edit option is not set, the
current cursor character shall always be updated.
The following specifications are for command characters entered
during text input mode.
NUL
Synopsis:
NUL
If the first character of the text input is a NUL, the most recently
input text shall be input as if entered by the user, and then text
input mode shall be exited. The text shall be input literally; that
is, characters are neither macro or abbreviation expanded, nor are
any characters interpreted in any special manner. It is unspecified
whether implementations shall support more than 256 bytes of
remembered input text.
<control>-D
Synopsis:
<control>-D
The <control>‐D character shall have no special meaning when in text
input mode for a line-oriented command (see Command Descriptions in
vi).
This command need not be supported on block-mode terminals.
If the cursor does not follow an autoindent character, or an
autoindent character and a '0' or '^' character:
1. If the cursor is in column position 1, the <control>‐D character
shall be discarded and no further action taken.
2. Otherwise, the <control>‐D character shall have no special
meaning.
If the last input character was a '0', the cursor shall be moved to
column position 1.
Otherwise, if the last input character was a '^', the cursor shall be
moved to column position 1. In addition, the autoindent level for the
next input line shall be derived from the same line from which the
autoindent level for the current input line was derived.
Otherwise, the cursor shall be moved back to the column after the
previous shiftwidth (see the ex shiftwidth command) boundary.
All of the glyphs on columns between the starting cursor position and
(inclusively) the ending cursor position shall become erase-columns
as described in Input Mode Commands in vi.
Current line: Unchanged.
Current column: Set to 1 if the <control>‐D was preceded by a '^' or
'0'; otherwise, set to (column −1) −((column −2) % shiftwidth).
<control>-H
Synopsis:
<control>-H
If in text input mode for a line-oriented command, and there are no
characters to erase, text input mode shall be terminated, no further
action shall be done for this command, and the current line and
column shall be unchanged.
If there are characters other than autoindent characters that have
been input on the current line before the cursor, the cursor shall
move back one character.
Otherwise, if there are autoindent characters on the current line
before the cursor, it is implementation-defined whether the
<control>‐H command is an error or if the cursor moves back one
autoindent character.
Otherwise, if the cursor is in column position 1 and there are
previous lines that have been input, it is implementation-defined
whether the <control>‐H command is an error or if it is equivalent to
entering <control>‐H after the last input character on the previous
input line.
Otherwise, it shall be an error.
All of the glyphs on columns between the starting cursor position and
(inclusively) the ending cursor position shall become erase-columns
as described in Input Mode Commands in vi.
The current erase character (see stty) shall cause an equivalent
action to the <control>‐H command, unless the previously inserted
character was a <backslash>, in which case it shall be as if the
literal current erase character had been inserted instead of the
<backslash>.
Current line: Unchanged, unless previously input lines are erased, in
which case it shall be set to line −1.
Current column: Set to the first column that displays any portion of
the character backed up over.
<newline>
Synopsis:
<newline>
<carriage-return>
<control>-J
<control>-M
If input was part of a line-oriented command, text input mode shall
be terminated and the command shall continue execution with the input
provided.
Otherwise, terminate the current line. If there are no characters
other than autoindent characters on the line, all characters on the
line shall be discarded. Otherwise, it is unspecified whether the
autoindent characters in the line are modified by entering these
characters.
Continue text input mode on a new line appended after the current
line. If the slowopen edit option is set, the lines on the screen
below the current line shall not be pushed down, but the first of
them shall be cleared and shall appear to be overwritten. Otherwise,
the lines of the screen below the current line shall be pushed down.
If the autoindent edit option is set, an appropriate number of
autoindent characters shall be added as a prefix to the line as
described by the ex autoindent edit option.
All columns after the cursor that are erase-columns (as described in
Input Mode Commands in vi) shall be discarded.
If the autoindent edit option is set, all <blank> characters
immediately following the cursor shall be discarded.
All remaining characters after the cursor shall be transferred to the
new line, positioned after any autoindent characters.
Current line: Set to current line +1.
Current column: Set to the first column that displays any portion of
the first character after the autoindent characters on the new line,
if any, or the first column position after the last autoindent
character, if any, or column position 1.
<control>-T
Synopsis:
<control>-T
The <control>‐T character shall have no special meaning when in text
input mode for a line-oriented command (see Command Descriptions in
vi).
This command need not be supported on block-mode terminals.
Behave as if the user entered the minimum number of <blank>
characters necessary to move the cursor forward to the column
position after the next shiftwidth (see the ex shiftwidth command)
boundary.
Current line: Unchanged.
Current column: Set to column + shiftwidth − ((column −1) %
shiftwidth).
<control>-U
Synopsis:
<control>-U
If there are characters other than autoindent characters that have
been input on the current line before the cursor, the cursor shall
move to the first character input after the autoindent characters.
Otherwise, if there are autoindent characters on the current line
before the cursor, it is implementation-defined whether the
<control>‐U command is an error or if the cursor moves to the first
column position on the line.
Otherwise, if the cursor is in column position 1 and there are
previous lines that have been input, it is implementation-defined
whether the <control>‐U command is an error or if it is equivalent to
entering <control>‐U after the last input character on the previous
input line.
Otherwise, it shall be an error.
All of the glyphs on columns between the starting cursor position and
(inclusively) the ending cursor position shall become erase-columns
as described in Input Mode Commands in vi.
The current kill character (see stty) shall cause an equivalent
action to the <control>‐U command, unless the previously inserted
character was a <backslash>, in which case it shall be as if the
literal current kill character had been inserted instead of the
<backslash>.
Current line: Unchanged, unless previously input lines are erased, in
which case it shall be set to line −1.
Current column: Set to the first column that displays any portion of
the last character backed up over.
<control>-V
Synopsis:
<control>-V
<control>-Q
Allow the entry of any subsequent character, other than <control>‐J
or the <newline>, as a literal character, removing any special
meaning that it may have to the editor in text input mode. If a
<control>‐V or <control>‐Q is entered before a <control>‐J or
<newline>, the <control>‐V or <control>‐Q character shall be
discarded, and the <control>‐J or <newline> shall behave as described
in the <newline> command character during input mode.
For purposes of the display only, the editor shall behave as if a '^'
character was entered, and the cursor shall be positioned as if
overwriting the '^' character. When a subsequent character is
entered, the editor shall behave as if that character was entered
instead of the original <control>‐V or <control>‐Q character.
Current line: Unchanged.
Current column: Unchanged.
<control>-W
Synopsis:
<control>-W
If there are characters other than autoindent characters that have
been input on the current line before the cursor, the cursor shall
move back over the last word preceding the cursor (including any
<blank> characters between the end of the last word and the current
cursor); the cursor shall not move to before the first character
after the end of any autoindent characters.
Otherwise, if there are autoindent characters on the current line
before the cursor, it is implementation-defined whether the
<control>‐W command is an error or if the cursor moves to the first
column position on the line.
Otherwise, if the cursor is in column position 1 and there are
previous lines that have been input, it is implementation-defined
whether the <control>‐W command is an error or if it is equivalent to
entering <control>‐W after the last input character on the previous
input line.
Otherwise, it shall be an error.
All of the glyphs on columns between the starting cursor position and
(inclusively) the ending cursor position shall become erase-columns
as described in Input Mode Commands in vi.
Current line: Unchanged, unless previously input lines are erased, in
which case it shall be set to line −1.
Current column: Set to the first column that displays any portion of
the last character backed up over.
<ESC>
Synopsis:
<ESC>
If input was part of a line-oriented command:
1. If interrupt was entered, text input mode shall be terminated and
the editor shall return to command mode. The terminal shall be
alerted.
2. If <ESC> was entered, text input mode shall be terminated and the
command shall continue execution with the input provided.
Otherwise, terminate text input mode and return to command mode.
Any autoindent characters entered on newly created lines that have no
other non-<newline> characters shall be deleted.
Any leading autoindent and <blank> characters on newly created lines
shall be rewritten to be the minimum number of <blank> characters
possible.
The screen shall be redisplayed as necessary to match the contents of
the edit buffer.
Current line: Unchanged.
Current column:
1. If there are text input characters on the current line, the
column shall be set to the last column where any portion of the
last text input character is displayed.
2. Otherwise, if a character is displayed in the current column,
unchanged.
3. Otherwise, set to column position 1.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
When any error is encountered and the standard input is not a
terminal device file, vi shall not write the file or return to
command or text input mode, and shall terminate with a non-zero exit
status.
Otherwise, when an unrecoverable error is encountered it shall be
equivalent to a SIGHUP asynchronous event.
Otherwise, when an error is encountered, the editor shall behave as
specified in Command Descriptions in vi.
The following sections are informative.
None.
None.
See the RATIONALE for ex(1p) for more information on vi. Major
portions of the vi utility specification point to ex to avoid
inadvertent divergence. While ex and vi have historically been
implemented as a single utility, this is not required by
POSIX.1‐2008.
It is recognized that portions of vi would be difficult, if not
impossible, to implement satisfactorily on a block-mode terminal, or
a terminal without any form of cursor addressing, thus it is not a
mandatory requirement that such features should work on all
terminals. It is the intention, however, that a vi implementation
should provide the full set of capabilities on all terminals capable
of supporting them.
Historically, vi exited immediately if the standard input was not a
terminal. POSIX.1‐2008 permits, but does not require, this behavior.
An end-of-file condition is not equivalent to an end-of-file
character. A common end-of-file character, <control>‐D, is
historically a vi command.
The text in the STDOUT section reflects the usage of the verb display
in this section; some implementations of vi use standard output to
write to the terminal, but POSIX.1‐2008 does not require that to be
the case.
Historically, implementations reverted to open mode if the terminal
was incapable of supporting full visual mode. POSIX.1‐2008 requires
this behavior. Historically, the open mode of vi behaved roughly
equivalently to the visual mode, with the exception that only a
single line from the edit buffer (one ``buffer line'') was kept
current at any time. This line was normally displayed on the next-to-
last line of a terminal with cursor addressing (and the last line
performed its normal visual functions for line-oriented commands and
messages). In addition, some few commands behaved differently in open
mode than in visual mode. POSIX.1‐2008 requires conformance to
historical practice.
Historically, ex and vi implementations have expected text to proceed
in the usual European/Latin order of left to right, top to bottom.
There is no requirement in POSIX.1‐2008 that this be the case. The
specification was deliberately written using words like ``before'',
``after'', ``first'', and ``last'' in order to permit implementations
to support the natural text order of the language.
Historically, lines past the end of the edit buffer were marked with
single <tilde> ('~') characters; that is, if the one-based display
was 20 lines in length, and the last line of the file was on line
one, then lines 2-20 would contain only a single '~' character.
Historically, the vi editor attempted to display only complete lines
at the bottom of the screen (it did display partial lines at the top
of the screen). If a line was too long to fit in its entirety at the
bottom of the screen, the screen lines where the line would have been
displayed were displayed as single '@' characters, instead of
displaying part of the line. POSIX.1‐2008 permits, but does not
require, this behavior. Implementations are encouraged to attempt
always to display a complete line at the bottom of the screen when
doing scrolling or screen positioning by buffer lines.
Historically, lines marked with '@' were also used to minimize output
to dumb terminals over slow lines; that is, changes local to the
cursor were updated, but changes to lines on the screen that were not
close to the cursor were simply marked with an '@' sign instead of
being updated to match the current text. POSIX.1‐2008 permits, but
does not require this feature because it is used ever less frequently
as terminals become smarter and connections are faster.
Initialization in ex and vi
Historically, vi always had a line in the edit buffer, even if the
edit buffer was ``empty''. For example:
1. The ex command = executed from visual mode wrote ``1'' when the
buffer was empty.
2. Writes from visual mode of an empty edit buffer wrote files of a
single character (a <newline>), while writes from ex mode of an
empty edit buffer wrote empty files.
3. Put and read commands into an empty edit buffer left an empty
line at the top of the edit buffer.
For consistency, POSIX.1‐2008 does not permit any of these behaviors.
Historically, vi did not always return the terminal to its original
modes; for example, ICRNL was modified if it was not originally set.
POSIX.1‐2008 does not permit this behavior.
Command Descriptions in vi
Motion commands are among the most complicated aspects of vi to
describe. With some exceptions, the text region and buffer type
effect of a motion command on a vi command are described on a case-
by-case basis. The descriptions of text regions in POSIX.1‐2008 are
not intended to imply direction; that is, an inclusive region from
line n to line n+5 is identical to a region from line n+5 to line n.
This is of more than academic interest—movements to marks can be in
either direction, and, if the wrapscan option is set, so can
movements to search points. Historically, lines are always stored
into buffers in text order; that is, from the start of the edit
buffer to the end. POSIX.1‐2008 requires conformance to historical
practice.
Historically, command counts were applied to any associated motion,
and were multiplicative to any supplied motion count. For example,
2cw is the same as c2w, and 2c3w is the same as c6w. POSIX.1‐2008
requires this behavior. Historically, vi commands that used bigwords,
words, paragraphs, and sentences as objects treated groups of empty
lines, or lines that contained only <blank> characters,
inconsistently. Some commands treated them as a single entity, while
others treated each line separately. For example, the w, W, and B
commands treated groups of empty lines as individual words; that is,
the command would move the cursor to each new empty line. The e and E
commands treated groups of empty lines as a single word; that is, the
first use would move past the group of lines. The b command would
just beep at the user, or if done from the start of the line as a
motion command, fail in unexpected ways. If the lines contained only
(or ended with) <blank> characters, the w and W commands would just
beep at the user, the E and e commands would treat the group as a
single word, and the B and b commands would treat the lines as
individual words. For consistency and simplicity of specification,
POSIX.1‐2008 requires that all vi commands treat groups of empty or
blank lines as a single entity, and that movement through lines
ending with <blank> characters be consistent with other movements.
Historically, vi documentation indicated that any number of double-
quotes were skipped after punctuation marks at sentence boundaries;
however, implementations only skipped single-quotes. POSIX.1‐2008
requires both to be skipped.
Historically, the first and last characters in the edit buffer were
word boundaries. This historical practice is required by
POSIX.1‐2008.
Historically, vi attempted to update the minimum number of columns on
the screen possible, which could lead to misleading information being
displayed. POSIX.1‐2008 makes no requirements other than that the
current character being entered is displayed correctly, leaving all
other decisions in this area up to the implementation.
Historically, lines were arbitrarily folded between columns of any
characters that required multiple column positions on the screen,
with the exception of tabs, which terminated at the right-hand
margin. POSIX.1‐2008 permits the former and requires the latter.
Implementations that do not arbitrarily break lines between columns
of characters that occupy multiple column positions should not permit
the cursor to rest on a column that does not contain any part of a
character.
The historical vi had a problem in that all movements were by buffer
lines, not by display or screen lines. This is often the right thing
to do; for example, single line movements, such as j or k, should
work on buffer lines. Commands like dj, or j., where . is a change
command, only make sense for buffer lines. It is not, however, the
right thing to do for screen motion or scrolling commands like
<control>‐D, <control>‐F, and H. If the window is fairly small,
using buffer lines in these cases can result in completely random
motion; for example, 1<control>‐D can result in a completely changed
screen, without any overlap. This is clearly not what the user
wanted. The problem is even worse in the case of the H, L, and M
commands—as they position the cursor at the first non-<blank> of the
line, they may all refer to the same location in large lines, and
will result in no movement at all.
In addition, if the line is larger than the screen, using buffer
lines can make it impossible to display parts of the line—there are
not any commands that do not display the beginning of the line in
historical vi, and if both the beginning and end of the line cannot
be on the screen at the same time, the user suffers. Finally, the
page and half-page scrolling commands historically moved to the first
non-<blank> in the new line. If the line is approximately the same
size as the screen, this is inadequate because the cursor before and
after a <control>‐D command will refer to the same location on the
screen.
Implementations of ex and vi exist that do not have these problems
because the relevant commands (<control>‐B, <control>‐D, <control>‐F,
<control>‐U, <control>‐Y, <control>‐E, H, L, and M) operate on
display (screen) lines, not (edit) buffer lines.
POSIX.1‐2008 does not permit this behavior by default because the
standard developers believed that users would find it too confusing.
However, historical practice has been relaxed. For example, ex and vi
historically attempted, albeit sometimes unsuccessfully, to never put
part of a line on the last lines of a screen; for example, if a line
would not fit in its entirety, no part of the line was displayed, and
the screen lines corresponding to the line contained single '@'
characters. This behavior is permitted, but not required by
POSIX.1‐2008, so that it is possible for implementations to support
long lines in small screens more reasonably without changing the
commands to be oriented to the display (instead of oriented to the
buffer). POSIX.1‐2008 also permits implementations to refuse to edit
any edit buffer containing a line that will not fit on the screen in
its entirety.
The display area (for example, the value of the window edit option)
has historically been ``grown'', or expanded, to display new text
when local movements are done in displays where the number of lines
displayed is less than the maximum possible. Expansion has
historically been the first choice, when the target line is less than
the maximum possible expansion value away. Scrolling has historically
been the next choice, done when the target line is less than half a
display away, and otherwise, the screen was redrawn. There were
exceptions, however, in that ex commands generally always caused the
screen to be redrawn. POSIX.1‐2008 does not specify a standard
behavior because there may be external issues, such as connection
speed, the number of characters necessary to redraw as opposed to
scroll, or terminal capabilities that implementations will have to
accommodate.
The current line in POSIX.1‐2008 maps one-to-one to a buffer line in
the file. The current column does not. There are two different column
values that are described by POSIX.1‐2008. The first is the current
column value as set by many of the vi commands. This value is
remembered for the lifetime of the editor. The second column value is
the actual position on the screen where the cursor rests. The two are
not always the same. For example, when the cursor is backed by a
multi-column character, the actual cursor position on the screen has
historically been the last column of the character in command mode,
and the first column of the character in input mode.
Commands that set the current line, but that do not set the current
cursor value (for example, j and k) attempt to get as close as
possible to the remembered column position, so that the cursor tends
to restrict itself to a vertical column as the user moves around in
the edit buffer. POSIX.1‐2008 requires conformance to historical
practice, requiring that the display location of the cursor on the
display line be adjusted from the current column value as necessary
to support this historical behavior.
Historically, only a single line (and for some terminals, a single
line minus 1 column) of characters could be entered by the user for
the line-oriented commands; that is, :, !, /, or ?. POSIX.1‐2008
permits, but does not require, this limitation.
Historically, ``soft'' errors in vi caused the terminal to be
alerted, but no error message was displayed. As a general rule, no
error message was displayed for errors in command execution in vi,
when the error resulted from the user attempting an invalid or
impossible action, or when a searched-for object was not found.
Examples of soft errors included h at the left margin, <control>‐B or
[[ at the beginning of the file, 2G at the end of the file, and so
on. In addition, errors such as %, ]], }, ), N, n, f, F, t, and T
failing to find the searched-for object were soft as well. Less
consistently, / and ? displayed an error message if the pattern was
not found, /, ?, N, and n displayed an error message if no previous
regular expression had been specified, and ; did not display an error
message if no previous f, F, t, or T command had occurred. Also,
behavior in this area might reasonably be based on a runtime
evaluation of the speed of a network connection. Finally, some
implementations have provided error messages for soft errors in order
to assist naive users, based on the value of a verbose edit option.
POSIX.1‐2008 does not list specific errors for which an error message
shall be displayed. Implementations should conform to historical
practice in the absence of any strong reason to diverge.
Page Backwards
The <control>‐B and <control>‐F commands historically considered it
an error to attempt to page past the beginning or end of the file,
whereas the <control>‐D and <control>‐U commands simply moved to the
beginning or end of the file. For consistency, POSIX.1‐2008 requires
the latter behavior for all four commands. All four commands still
consider it an error if the current line is at the beginning
(<control>‐B, <control>‐U) or end (<control>‐F, <control>‐D) of the
file. Historically, the <control>‐B and <control>‐F commands skip two
lines in order to include overlapping lines when a single command is
entered. This makes less sense in the presence of a count, as there
will be, by definition, no overlapping lines. The actual calculation
used by historical implementations of the vi editor for <control>‐B
was:
((current first line) − count x (window edit option)) +2
and for <control>‐F was:
((current first line) + count x (window edit option)) −2
This calculation does not work well when intermixing commands with
and without counts; for example, 3<control>‐F is not equivalent to
entering the <control>‐F command three times, and is not reversible
by entering the <control>‐B command three times. For consistency with
other vi commands that take counts, POSIX.1‐2008 requires a different
calculation.
Scroll Forward
The 4BSD and System V implementations of vi differed on the initial
value used by the scroll command. 4BSD used:
((window edit option) +1) /2
while System V used the value of the scroll edit option. The System V
version is specified by POSIX.1‐2008 because the standard developers
believed that it was more intuitive and permitted the user a method
of setting the scroll value initially without also setting the number
of lines that are displayed.
Scroll Forward by Line
Historically, the <control>‐E and <control>‐Y commands considered it
an error if the last and first lines, respectively, were already on
the screen. POSIX.1‐2008 requires conformance to historical practice.
Historically, the <control>‐E and <control>‐Y commands had no effect
in open mode. For simplicity and consistency of specification,
POSIX.1‐2008 requires that they behave as usual, albeit with a single
line screen.
Clear and Redisplay
The historical <control>‐L command refreshed the screen exactly as it
was supposed to be currently displayed, replacing any '@' characters
for lines that had been deleted but not updated on the screen with
refreshed '@' characters. The intent of the <control>‐L command is to
refresh when the screen has been accidentally overwritten; for
example, by a write command from another user, or modem noise.
Redraw Screen
The historical <control>‐R command redisplayed only when necessary to
update lines that had been deleted but not updated on the screen and
that were flagged with '@' characters. There is no requirement that
the screen be in any way refreshed if no lines of this form are
currently displayed. POSIX.1‐2008 permits implementations to extend
this command to refresh lines on the screen flagged with '@'
characters because they are too long to be displayed in the current
framework; however, the current line and column need not be modified.
Search for tagstring
Historically, the first non-<blank> at or after the cursor was the
first character, and all subsequent characters that were word
characters, up to the end of the line, were included. For example,
with the cursor on the leading <space> or on the '#' character in the
text "#bar@", the tag was "#bar". On the character 'b' it was "bar",
and on the 'a' it was "ar". POSIX.1‐2008 requires this behavior.
Replace Text with Results from Shell Command
Historically, the <, >, and ! commands considered most cursor
motions other than line-oriented motions an error; for example, the
command >/foo<CR> succeeded, while the command >l failed, even though
the text region described by the two commands might be identical. For
consistency, all three commands only consider entire lines and not
partial lines, and the region is defined as any line that contains a
character that was specified by the motion.
Move to Matching Character
Other matching characters have been left implementation-defined in
order to allow extensions such as matching '<' and '>' for searching
HTML, or #ifdef, #else, and #endif for searching C source.
Repeat Substitution
POSIX.1‐2008 requires that any c and g flags specified to the
previous substitute command be ignored; however, the r flag may still
apply, if supported by the implementation.
Return to Previous (Context or Section)
The [[, ]], (, ), {, and } commands are all affected by ``section
boundaries'', but in some historical implementations not all of the
commands recognize the same section boundaries. This is a bug, not a
feature, and a unique section-boundary algorithm was not described
for each command. One special case that is preserved is that the
sentence command moves to the end of the last line of the edit buffer
while the other commands go to the beginning, in order to preserve
the traditional character cut semantics of the sentence command.
Historically, vi section boundaries at the beginning and end of the
edit buffer were the first non-<blank> on the first and last lines of
the edit buffer if one exists; otherwise, the last character of the
first and last lines of the edit buffer if one exists. To increase
consistency with other section locations, this has been simplified by
POSIX.1‐2008 to the first character of the first and last lines of
the edit buffer, or the first and the last lines of the edit buffer
if they are empty.
Sentence boundaries were problematic in the historical vi. They were
not only the boundaries as defined for the section and paragraph
commands, but they were the first non-<blank> that occurred after
those boundaries, as well. Historically, the vi section commands were
documented as taking an optional window size as a count preceding the
command. This was not implemented in historical versions, so
POSIX.1‐2008 requires that the count repeat the command, for
consistency with other vi commands.
Repeat
Historically, mapped commands other than text input commands could
not be repeated using the period command. POSIX.1‐2008 requires
conformance to historical practice.
The restrictions on the interpretation of special characters (for
example, <control>‐H) in the repetition of text input mode commands
is intended to match historical practice. For example, given the
input sequence:
iab<control>-H<control>-H<control>-Hdef<escape>
the user should be informed of an error when the sequence is first
entered, but not during a command repetition. The character
<control>‐T is specifically exempted from this restriction.
Historical implementations of vi ignored <control>‐T characters that
were input in the original command during command repetition.
POSIX.1‐2008 prohibits this behavior.
Find Regular Expression
Historically, commands did not affect the line searched to or from if
the motion command was a search (/, ?, N, n) and the final position
was the start/end of the line. There were some special cases and vi
was not consistent. POSIX.1‐2008 does not permit this behavior, for
consistency. Historical implementations permitted but were unable to
handle searches as motion commands that wrapped (that is, due to the
edit option wrapscan) to the original location. POSIX.1‐2008 requires
that this behavior be treated as an error.
Historically, the syntax "/RE/0" was used to force the command to cut
text in line mode. POSIX.1‐2008 requires conformance to historical
practice.
Historically, in open mode, a z specified to a search command
redisplayed the current line instead of displaying the current screen
with the current line highlighted. For consistency and simplicity of
specification, POSIX.1‐2008 does not permit this behavior.
Historically, trailing z commands were permitted and ignored if
entered as part of a search used as a motion command. For consistency
and simplicity of specification, POSIX.1‐2008 does not permit this
behavior.
Execute an ex Command
Historically, vi implementations restricted the commands that could
be entered on the colon command line (for example, append and
change), and some other commands were known to cause them to fail
catastrophically. For consistency, POSIX.1‐2008 does not permit these
restrictions. When executing an ex command by entering :, it is not
possible to enter a <newline> as part of the command because it is
considered the end of the command. A different approach is to enter
ex command mode by using the vi Q command (and later resuming visual
mode with the ex vi command). In ex command mode, the single-line
limitation does not exist. So, for example, the following is valid:
Q
s/break here/break\
here/
vi
POSIX.1‐2008 requires that, if the ex command overwrites any part of
the screen that would be erased by a refresh, vi pauses for a
character from the user. Historically, this character could be any
character; for example, a character input by the user before the
message appeared, or even a mapped character. This is probably a bug,
but implementations that have tried to be more rigorous by requiring
that the user enter a specific character, or that the user enter a
character after the message was displayed, have been forced by user
indignation back into historical behavior. POSIX.1‐2008 requires
conformance to historical practice.
Shift Left (Right)
Refer to the Rationale for the ! and / commands. Historically, the <
and > commands sometimes moved the cursor to the first non-<blank>
(for example if the command was repeated or with _ as the motion
command), and sometimes left it unchanged. POSIX.1‐2008 does not
permit this inconsistency, requiring instead that the cursor always
move to the first non-<blank>. Historically, the < and > commands
did not support buffer arguments, although some implementations allow
the specification of an optional buffer. This behavior is neither
required nor disallowed by POSIX.1‐2008.
Execute
Historically, buffers could execute other buffers, and loops,
infinite and otherwise, were possible. POSIX.1‐2008 requires
conformance to historical practice. The *buffer syntax of ex is not
required in vi, because it is not historical practice and has been
used in some vi implementations to support additional scripting
languages.
Reverse Case
Historically, the ~ command ignored any associated count, and acted
only on the characters in the current line. For consistency with
other vi commands, POSIX.1‐2008 requires that an associated count act
on the next count characters, and that the command move to subsequent
lines if warranted by count, to make it possible to modify large
pieces of text in a reasonably efficient manner. There exist vi
implementations that optionally require an associated motion command
for the ~ command. Implementations supporting this functionality are
encouraged to base it on the tildedop edit option and handle the text
regions and cursor positioning identically to the yank command.
Append
Historically, counts specified to the A, a, I, and i commands
repeated the input of the first line count times, and did not repeat
the subsequent lines of the input text. POSIX.1‐2008 requires that
the entire text input be repeated count times.
Move Backward to Preceding Word
Historically, vi became confused if word commands were used as motion
commands in empty files. POSIX.1‐2008 requires that this be an error.
Historical implementations of vi had a large number of bugs in the
word movement commands, and they varied greatly in behavior in the
presence of empty lines, ``words'' made up of a single character, and
lines containing only <blank> characters. For consistency and
simplicity of specification, POSIX.1‐2008 does not permit this
behavior.
Change to End-of-Line
Some historical implementations of the C command did not behave as
described by POSIX.1‐2008 when the $ key was remapped because they
were implemented by pushing the $ key onto the input queue and
reprocessing it. POSIX.1‐2008 does not permit this behavior.
Historically, the C, S, and s commands did not copy replaced text
into the numeric buffers. For consistency and simplicity of
specification, POSIX.1‐2008 requires that they behave like their
respective c commands in all respects.
Delete
Historically, lines in open mode that were deleted were scrolled up,
and an @ glyph written over the beginning of the line. In the case of
terminals that are incapable of the necessary cursor motions, the
editor erased the deleted line from the screen. POSIX.1‐2008 requires
conformance to historical practice; that is, if the terminal cannot
display the '@' character, the line cannot remain on the screen.
Delete to End-of-Line
Some historical implementations of the D command did not behave as
described by POSIX.1‐2008 when the $ key was remapped because they
were implemented by pushing the $ key onto the input queue and
reprocessing it. POSIX.1‐2008 does not permit this behavior.
Join
An historical oddity of vi is that the commands J, 1J, and 2J are all
equivalent. POSIX.1‐2008 requires conformance to historical practice.
The vi J command is specified in terms of the ex join command with an
ex command count value. The address correction for a count that is
past the end of the edit buffer is necessary for historical
compatibility for both ex and vi.
Mark Position
Historical practice is that only lowercase letters, plus backquote
and single-quote, could be used to mark a cursor position.
POSIX.1‐2008 requires conformance to historical practice, but
encourages implementations to support other characters as marks as
well.
Repeat Regular Expression Find (Forward and Reverse)
Historically, the N and n commands could not be used as motion
components for the c command. With the exception of the cN command,
which worked if the search crossed a line boundary, the text region
would be discarded, and the user would not be in text input mode. For
consistency and simplicity of specification, POSIX.1‐2008 does not
permit this behavior.
Insert Empty Line (Below and Above)
Historically, counts to the O and o commands were used as the number
of physical lines to open, if the terminal was dumb and the slowopen
option was not set. This was intended to minimize traffic over slow
connections and repainting for dumb terminals. POSIX.1‐2008 does not
permit this behavior, requiring that a count to the open command
behave as for other text input commands. This change to historical
practice was made for consistency, and because a superset of the
functionality is provided by the slowopen edit option.
Put from Buffer (Following and Before)
Historically, counts to the p and P commands were ignored if the
buffer was a line mode buffer, but were (mostly) implemented as
described in POSIX.1‐2008 if the buffer was a character mode buffer.
Because implementations exist that do not have this limitation, and
because pasting lines multiple times is generally useful,
POSIX.1‐2008 requires that count be supported for all p and P
commands.
Historical implementations of vi were widely known to have major
problems in the p and P commands, particularly when unusual regions
of text were copied into the edit buffer. The standard developers
viewed these as bugs, and they are not permitted for consistency and
simplicity of specification.
Historically, a P or p command (or an ex put command executed from
open or visual mode) executed in an empty file, left an empty line as
the first line of the file. For consistency and simplicity of
specification, POSIX.1‐2008 does not permit this behavior.
Replace Character
Historically, the r command did not correctly handle the erase and
word erase characters as arguments, nor did it handle an associated
count greater than 1 with a <carriage-return> argument, for which it
replaced count characters with a single <newline>. POSIX.1‐2008 does
not permit these inconsistencies.
Historically, the r command permitted the <control>‐V escaping of
entered characters, such as <ESC> and the <carriage-return>; however,
it required two leading <control>‐V characters instead of one.
POSIX.1‐2008 requires that this be changed for consistency with the
other text input commands of vi.
Historically, it is an error to enter the r command if there are less
than count characters at or after the cursor in the line. While a
reasonable and unambiguous extension would be to permit the r command
on empty lines, it would require that too large a count be adjusted
to match the number of characters at or after the cursor for
consistency, which is sufficiently different from historical practice
to be avoided. POSIX.1‐2008 requires conformance to historical
practice.
Replace Characters
Historically, if there were autoindent characters in the line on
which the R command was run, and autoindent was set, the first
<newline> would be properly indented and no characters would be
replaced by the <newline>. Each additional <newline> would replace n
characters, where n was the number of characters that were needed to
indent the rest of the line to the proper indentation level. This
behavior is a bug and is not permitted by POSIX.1‐2008.
Undo
Historical practice for cursor positioning after undoing commands was
mixed. In most cases, when undoing commands that affected a single
line, the cursor was moved to the start of added or changed text, or
immediately after deleted text. However, if the user had moved from
the line being changed, the column was either set to the first
non-<blank>, returned to the origin of the command, or remained
unchanged. When undoing commands that affected multiple lines or
entire lines, the cursor was moved to the first character in the
first line restored. As an example of how inconsistent this was, a
search, followed by an o text input command, followed by an undo
would return the cursor to the location where the o command was
entered, but a cw command followed by an o command followed by an
undo would return the cursor to the first non-<blank> of the line.
POSIX.1‐2008 requires the most useful of these behaviors, and
discards the least useful, in the interest of consistency and
simplicity of specification.
Yank
Historically, the yank command did not move to the end of the motion
if the motion was in the forward direction. It moved to the end of
the motion if the motion was in the backward direction, except for
the _ command, or for the G and ' commands when the end of the motion
was on the current line. This was further complicated by the fact
that for a number of motion commands, the yank command moved the
cursor but did not update the screen; for example, a subsequent
command would move the cursor from the end of the motion, even though
the cursor on the screen had not reflected the cursor movement for
the yank command. POSIX.1‐2008 requires that all yank commands
associated with backward motions move the cursor to the end of the
motion for consistency, and specifically, to make ' commands as
motions consistent with search patterns as motions.
Yank Current Line
Some historical implementations of the Y command did not behave as
described by POSIX.1‐2008 when the '_' key was remapped because they
were implemented by pushing the '_' key onto the input queue and
reprocessing it. POSIX.1‐2008 does not permit this behavior.
Redraw Window
Historically, the z command always redrew the screen. This is
permitted but not required by POSIX.1‐2008, because of the frequent
use of the z command in macros such as map n nz. for screen
positioning, instead of its use to change the screen size. The
standard developers believed that expanding or scrolling the screen
offered a better interface for users. The ability to redraw the
screen is preserved if the optional new window size is specified, and
in the <control>‐L and <control>‐R commands.
The semantics of z^ are confusing at best. Historical practice is
that the screen before the screen that ended with the specified line
is displayed. POSIX.1‐2008 requires conformance to historical
practice.
Historically, the z command would not display a partial line at the
top or bottom of the screen. If the partial line would normally have
been displayed at the bottom of the screen, the command worked, but
the partial line was replaced with '@' characters. If the partial
line would normally have been displayed at the top of the screen, the
command would fail. For consistency and simplicity of specification,
POSIX.1‐2008 does not permit this behavior.
Historically, the z command with a line specification of 1 ignored
the command. For consistency and simplicity of specification,
POSIX.1‐2008 does not permit this behavior.
Historically, the z command did not set the cursor column to the
first non-<blank> for the character if the first screen was to be
displayed, and was already displayed. For consistency and simplicity
of specification, POSIX.1‐2008 does not permit this behavior.
Input Mode Commands in vi
Historical implementations of vi did not permit the user to erase
more than a single line of input, or to use normal erase characters
such as line erase, worderase, and erase to erase autoindent
characters. As there exist implementations of vi that do not have
these limitations, both behaviors are permitted, but only historical
practice is required. In the case of these extensions, vi is required
to pause at the autoindent and previous line boundaries.
Historical implementations of vi updated only the portion of the
screen where the current cursor character was displayed. For example,
consider the vi input keystrokes:
iabcd<escape>0C<tab>
Historically, the <tab> would overwrite the characters "abcd" when it
was displayed. Other implementations replace only the 'a' character
with the <tab>, and then push the rest of the characters ahead of the
cursor. Both implementations have problems. The historical
implementation is probably visually nicer for the above example;
however, for the keystrokes:
iabcd<ESC>0R<tab><ESC>
the historical implementation results in the string "bcd"
disappearing and then magically reappearing when the <ESC> character
is entered. POSIX.1‐2008 requires the former behavior when
overwriting erase-columns—that is, overwriting characters that are no
longer logically part of the edit buffer—and the latter behavior
otherwise.
Historical implementations of vi discarded the <control>‐D and
<control>‐T characters when they were entered at places where their
command functionality was not appropriate. POSIX.1‐2008 requires that
the <control>‐T functionality always be available, and that
<control>‐D be treated as any other key when not operating on
autoindent characters.
NUL
Some historical implementations of vi limited the number of
characters entered using the NUL input character to 256 bytes.
POSIX.1‐2008 permits this limitation; however, implementations are
encouraged to remove this limit.
<control>‐D
See also Rationale for the input mode command <newline>. The hidden
assumptions in the <control>‐D command (and in the vi autoindent
specification in general) is that <space> characters take up a single
column on the screen and that <tab> characters are comprised of an
integral number of <space> characters.
<newline>
Implementations are permitted to rewrite autoindent characters in the
line when <newline>, <carriage-return>, <control>‐D, and <control>‐T
are entered, or when the shift commands are used, because historical
implementations have both done so and found it necessary to do so.
For example, a <control>‐D when the cursor is preceded by a single
<tab>, with tabstop set to 8, and shiftwidth set to 3, will result in
the <tab> being replaced by several <space> characters.
<control>‐T
See also the Rationale for the input mode command <newline>.
Historically, <control>‐T only worked if no non-<blank> characters
had yet been input in the current input line. In addition, the
characters inserted by <control>‐T were treated as autoindent
characters, and could not be erased using normal user erase
characters. Because implementations exist that do not have these
limitations, and as moving to a column boundary is generally useful,
POSIX.1‐2008 requires that both limitations be removed.
<control>‐V
Historically, vi used ^V, regardless of the value of the literal-next
character of the terminal. POSIX.1‐2008 requires conformance to
historical practice.
The uses described for <control>‐V can also be accomplished with
<control>‐Q, which is useful on terminals that use <control>‐V for
the down-arrow function. However, most historical implementations use
<control>‐Q for the termios START character, so the editor will
generally not receive the <control>‐Q unless stty ixon mode is set to
off. (In addition, some historical implementations of vi explicitly
set ixon mode to on, so it was difficult for the user to set it to
off.) Any of the command characters described in POSIX.1‐2008 can be
made ineffective by their selection as termios control characters,
using the stty utility or other methods described in the System
Interfaces volume of POSIX.1‐2008.
<ESC>
Historically, SIGINT alerted the terminal when used to end input
mode. This behavior is permitted, but not required, by POSIX.1‐2008.
None.
ed(1p), ex(1p), stty(1p)
The Base Definitions volume of POSIX.1‐2008, Section 12.2, Utility
Syntax Guidelines
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 VI(1P)
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