INDENT(1L) INDENT(1L)
indent - changes the appearance of a C program by inserting or delet‐
ing whitespace.
SYNOPSIS top
indent [options] [input-files]
indent [options] [single-input-file] [-o output-file]
indent --version
DESCRIPTION top
This man page is generated from the file indent.texinfo. This is
Edition of "The indent Manual", for Indent Version , last updated .
The indent program can be used to make code easier to read. It can
also convert from one style of writing C to another.
indent understands a substantial amount about the syntax of C, but it
also attempts to cope with incomplete and misformed syntax.
In version 1.2 and more recent versions, the GNU style of indenting
is the default.
OPTIONS top
-bad, --blank-lines-after-declarations
Force blank lines after the declarations.
See BLANK LINES.
-bap, --blank-lines-after-procedures
Force blank lines after procedure bodies.
See BLANK LINES.
-bbb, --blank-lines-before-block-comments
Force blank lines before block comments.
See BLANK LINES.
-bbo, --break-before-boolean-operator
Prefer to break long lines before boolean operators.
See BREAKING LONG LINES.
-bc, --blank-lines-after-commas
Force newline after comma in declaration.
See DECLARATIONS.
-bl, --braces-after-if-line
Put braces on line after if, etc.
See STATEMENTS.
-blf, --braces-after-func-def-line
Put braces on line following function definition line.
See DECLARATIONS.
-blin, --brace-indentn
Indent braces n spaces.
See STATEMENTS.
-bls, --braces-after-struct-decl-line
Put braces on the line after struct declaration lines.
See DECLARATIONS.
-br, --braces-on-if-line
Put braces on line with if, etc.
See STATEMENTS.
-brf, --braces-on-func-def-line
Put braces on function definition line.
See DECLARATIONS.
-brs, --braces-on-struct-decl-line
Put braces on struct declaration line.
See DECLARATIONS.
-bs, --Bill-Shannon, --blank-before-sizeof
Put a space between sizeof and its argument.
See STATEMENTS.
-cn, --comment-indentationn
Put comments to the right of code in column n.
See COMMENTS.
-cbin, --case-brace-indentationn
Indent braces after a case label N spaces.
See STATEMENTS.
-cdn, --declaration-comment-columnn
Put comments to the right of the declarations in column n.
See COMMENTS.
-cdb, --comment-delimiters-on-blank-lines
Put comment delimiters on blank lines.
See COMMENTS.
-cdw, --cuddle-do-while
Cuddle while of do {} while; and preceding ‘}’.
See COMMENTS.
-ce, --cuddle-else
Cuddle else and preceding ‘}’.
See COMMENTS.
-cin, --continuation-indentationn
Continuation indent of n spaces.
See STATEMENTS.
-clin, --case-indentationn
Case label indent of n spaces.
See STATEMENTS.
-cpn, --else-endif-columnn
Put comments to the right of #else and #endif statements in
column n.
See COMMENTS.
-cs, --space-after-cast
Put a space after a cast operator.
See STATEMENTS.
-dn, --line-comments-indentationn
Set indentation of comments not to the right of code to n spaces.
See COMMENTS.
-bfda, --break-function-decl-args
Break the line before all arguments in a declaration.
See DECLARATIONS.
-bfde, --break-function-decl-args-end
Break the line after the last argument in a declaration.
See DECLARATIONS.
-dj, --left-justify-declarations
If -cd 0 is used then comments after declarations are left
justified behind the declaration.
See DECLARATIONS.
-din, --declaration-indentationn
Put variables in column n.
See DECLARATIONS.
-fc1, --format-first-column-comments
Format comments in the first column.
See COMMENTS.
-fca, --format-all-comments
Do not disable all formatting of comments.
See COMMENTS.
-fnc, --fix-nested-comments
Fix nested comments.
See COMMENTS.
-gnu, --gnu-style
Use GNU coding style. This is the default.
See COMMON STYLES.
-gts, --gettext-strings
Treat gettext _("...") and N_("...") as strings rather than as
functions.
See BREAKING LONG LINES.
-hnl, --honour-newlines
Prefer to break long lines at the position of newlines in the
input.
See BREAKING LONG LINES.
-in, --indent-leveln
Set indentation level to n spaces.
See INDENTATION.
-iln, --indent-labeln
Set offset for labels to column n.
See INDENTATION.
-ipn, --parameter-indentationn
Indent parameter types in old-style function definitions by n
spaces.
See INDENTATION.
-kr, --k-and-r-style
Use Kernighan & Ritchie coding style.
See COMMON STYLES.
-ln, --line-lengthn
Set maximum line length for non-comment lines to n.
See BREAKING LONG LINES.
-lcn, --comment-line-lengthn
Set maximum line length for comment formatting to n.
See COMMENTS.
-linux, --linux-style
Use Linux coding style.
See COMMON STYLES.
-lp, --continue-at-parentheses
Line up continued lines at parentheses.
See INDENTATION.
-lps, --leave-preprocessor-space
Leave space between ‘#’ and preprocessor directive.
See INDENTATION.
-nbad, --no-blank-lines-after-declarations
Do not force blank lines after declarations.
See BLANK LINES.
-nbap, --no-blank-lines-after-procedures
Do not force blank lines after procedure bodies.
See BLANK LINES.
-nbbo, --break-after-boolean-operator
Do not prefer to break long lines before boolean operators.
See BREAKING LONG LINES.
-nbc, --no-blank-lines-after-commas
Do not force newlines after commas in declarations.
See DECLARATIONS.
-nbfda, --dont-break-function-decl-args
Don’t put each argument in a function declaration on a separate
line.
See DECLARATIONS.
-ncdb, --no-comment-delimiters-on-blank-lines
Do not put comment delimiters on blank lines.
See COMMENTS.
-ncdw, --dont-cuddle-do-while
Do not cuddle } and the while of a do {} while;.
See STATEMENTS.
-nce, --dont-cuddle-else
Do not cuddle } and else.
See STATEMENTS.
-ncs, --no-space-after-casts
Do not put a space after cast operators.
See STATEMENTS.
-ndjn, --dont-left-justify-declarations
Comments after declarations are treated the same as comments
after other statements.
See DECLARATIONS.
-nfc1, --dont-format-first-column-comments
Do not format comments in the first column as normal.
See COMMENTS.
-nfca, --dont-format-comments
Do not format any comments.
See COMMENTS.
-ngts, --no-gettext-strings
Treat gettext _("...") and N_("...") as normal functions. This
is the default.
See BREAKING LONG LINES.
-nhnl, --ignore-newlines
Do not prefer to break long lines at the position of newlines in
the input.
See BREAKING LONG LINES.
-nip, --no-parameter-indentation
Zero width indentation for parameters.
See INDENTATION.
-nlp, --dont-line-up-parentheses
Do not line up parentheses.
See STATEMENTS.
-npcs, --no-space-after-function-call-names
Do not put space after the function in function calls.
See STATEMENTS.
-nprs, --no-space-after-parentheses
Do not put a space after every ’(’ and before every ’)’.
See STATEMENTS.
-npsl, --dont-break-procedure-type
Put the type of a procedure on the same line as its name.
See DECLARATIONS.
-nsaf, --no-space-after-for
Do not put a space after every for.
See STATEMENTS.
-nsai, --no-space-after-if
Do not put a space after every if.
See STATEMENTS.
-nsaw, --no-space-after-while
Do not put a space after every while.
See STATEMENTS.
-nsc, --dont-star-comments
Do not put the ‘*’ character at the left of comments.
See COMMENTS.
-nsob, --leave-optional-blank-lines
Do not swallow optional blank lines.
See BLANK LINES.
-nss, --dont-space-special-semicolon
Do not force a space before the semicolon after certain
statements. Disables ‘-ss’.
See STATEMENTS.
-nut, --no-tabs
Use spaces instead of tabs.
See INDENTATION.
-nv, --no-verbosity
Disable verbose mode.
See MISCELLANEOUS OPTIONS.
-orig, --original
Use the original Berkeley coding style.
See COMMON STYLES.
-npro, --ignore-profile
Do not read ‘.indent.pro’ files.
See INVOKING INDENT.
-pal, --pointer-align-left
Put asterisks in pointer declarations on the left of spaces, next
to types: ‘‘char* p’’.
-par, --pointer-align-right
Put asterisks in pointer declarations on the right of spaces,
next to variable names: ‘‘char *p’’. This is the default
behavior.
-pcs, --space-after-procedure-calls
Insert a space between the name of the procedure being called and
the ‘(’.
See STATEMENTS.
-pin, --paren-indentationn
Specify the extra indentation per open parentheses ’(’ when a
statement is broken.See STATEMENTS.
-pmt, --preserve-mtime
Preserve access and modification times on output files.See
MISCELLANEOUS OPTIONS.
-ppin, --preprocessor-indentationn
Specify the indentation for preprocessor conditional
statements.See INDENTATION.
-prs, --space-after-parentheses
Put a space after every ’(’ and before every ’)’.
See STATEMENTS.
-psl, --procnames-start-lines
Put the type of a procedure on the line before its name.
See DECLARATIONS.
-saf, --space-after-for
Put a space after each for.
See STATEMENTS.
-sai, --space-after-if
Put a space after each if.
See STATEMENTS.
-saw, --space-after-while
Put a space after each while.
See STATEMENTS.
-sbin, --struct-brace-indentationn
Indent braces of a struct, union or enum N spaces.
See STATEMENTS.
-sc, --start-left-side-of-comments
Put the ‘*’ character at the left of comments.
See COMMENTS.
-sob, --swallow-optional-blank-lines
Swallow optional blank lines.
See BLANK LINES.
-ss, --space-special-semicolon
On one-line for and while statements, force a blank before the
semicolon.
See STATEMENTS.
-st, --standard-output
Write to standard output.
See INVOKING INDENT.
-T Tell indent the name of typenames.
See DECLARATIONS.
-tsn, --tab-sizen
Set tab size to n spaces.
See INDENTATION.
-ut, --use-tabs
Use tabs. This is the default.
See INDENTATION.
-v, --verbose
Enable verbose mode.
See MISCELLANEOUS OPTIONS.
-version
Output the version number of indent.
See MISCELLANEOUS OPTIONS.
INVOKING INDENT top
As of version 1.3, the format of the indent command is:
indent [options] [input-files]
indent [options] [single-input-file] [-o output-file]
This format is different from earlier versions and other versions of
indent.
In the first form, one or more input files are specified. indent
makes a backup copy of each file, and the original file is replaced
with its indented version. See BACKUP FILES, for an explanation of
how backups are made.
In the second form, only one input file is specified. In this case,
or when the standard input is used, you may specify an output file
after the ‘-o’ option.
To cause indent to write to standard output, use the ‘-st’ option.
This is only allowed when there is only one input file, or when the
standard input is used.
If no input files are named, the standard input is read for input.
Also, if a filename named ‘-’ is specified, then the standard input
is read.
As an example, each of the following commands will input the program
‘slithy_toves.c’ and write its indented text to ‘slithy_toves.out’:
indent slithy_toves.c -o slithy_toves.out
indent -st slithy_toves.c > slithy_toves.out
cat slithy_toves.c | indent -o slithy_toves.out
Most other options to indent control how programs are formatted. As
of version 1.2, indent also recognizes a long name for each option
name. Long options are prefixed by either ‘--’ or ‘+’. [ ‘+’ is
being superseded by ‘--’ to maintain consistency with the POSIX
standard.]
In most of this document, the traditional, short names are used for
the sake of brevity. See OPTION SUMMARY, for a list of options,
including both long and short names.
Here is another example:
indent -br test/metabolism.c -l85
This will indent the program ‘test/metabolism.c’ using the ‘-br’ and
‘-l85’ options, write the output back to ‘test/metabolism.c’, and
write the original contents of ‘test/metabolism.c’ to a backup file
in the directory ‘test’.
Equivalent invocations using long option names for this example would
be:
indent --braces-on-if-line --line-length185 test/metabolism.c
indent +braces-on-if-line +line-length185 test/metabolism.c
If you find that you often use indent with the same options, you may
put those options into a file named ‘.indent.pro’. indent will look
for a profile file in three places. First it will check the
environment variable INDENT_PROFILE. If that exists its value is
expected to name the file that is to be used. If the environment
variable does not exist, indent looks for ‘.indent.pro’ in the
current directory
and use that if found. Finally indent will search your home
directory for ‘.indent.pro’ and use that file if it is found. This
behaviour is different from that of other versions of indent, which
load both files if they both exist.
The format of ‘.indent.pro’ is simply a list of options, just as they
would appear on the command line, separated by white space (tabs,
spaces, and newlines). Options in ‘.indent.pro’ may be surrounded by
C or C++ comments, in which case they are ignored.
Command line switches are handled after processing ‘.indent.pro’.
Options specified later override arguments specified earlier, with
one exception: Explicitly specified options always override
background options (See COMMON STYLES). You can prevent indent from
reading an ‘.indent.pro’ file by specifying the ‘-npro’ option.
BACKUP FILES top
As of version 1.3, GNU indent makes GNU-style backup files, the same
way GNU Emacs does. This means that either simple or numbered backup
filenames may be made.
Simple backup file names are generated by appending a suffix to the
original file name. The default for this suffix is the one-character
string ‘~’ (tilde). Thus, the backup file for ‘python.c’ would be
‘python.c~’.
Instead of the default, you may specify any string as a suffix by
setting the environment variable SIMPLE_BACKUP_SUFFIX to your
preferred suffix.
Numbered backup versions of a file ‘momeraths.c’ look like
‘momeraths.c.~23~’, where 23 is the version of this particular
backup. When making a numbered backup of the file ‘src/momeraths.c’,
the backup file will be named ‘src/momeraths.c.~V~’, where V is one
greater than the highest version currently existing in the directory
‘src’. The environment variable VERSION_WIDTH controls the number of
digits, using left zero padding when necessary. For instance,
setting this variable to "2" will lead to the backup file being named
‘momeraths.c.~04~’.
The type of backup file made is controlled by the value of the
environment variable VERSION_CONTROL. If it is the string ‘simple’,
then only simple backups will be made. If its value is the string
‘numbered’, then numbered backups will be made. If its value is
‘numbered-existing’, then numbered backups will be made if there
already exist numbered backups for the file being indented;
otherwise, a simple backup is made. If VERSION_CONTROL is not set,
then indent assumes the behaviour of ‘numbered-existing’.
Other versions of indent use the suffix ‘.BAK’ in naming backup
files. This behaviour can be emulated by setting
SIMPLE_BACKUP_SUFFIX to ‘.BAK’.
Note also that other versions of indent make backups in the current
directory, rather than in the directory of the source file as GNU
indent now does.
COMMON STYLES top
There are several common styles of C code, including the GNU style,
the Kernighan & Ritchie style, and the original Berkeley style. A
style may be selected with a single background option, which
specifies a set of values for all other options. However, explicitly
specified options always override options implied by a background
option.
As of version 1.2, the default style of GNU indent is the GNU style.
Thus, it is no longer necessary to specify the option ‘-gnu’ to
obtain this format, although doing so will not cause an error.
Option settings which correspond to the GNU style are:
-nbad -bap -nbc -bbo -bl -bli2 -bls -ncdb -nce -cp1 -cs -di2
-ndj -nfc1 -nfca -hnl -i2 -ip5 -lp -pcs -nprs -psl -saf -sai
-saw -nsc -nsob
The GNU coding style is that preferred by the GNU project. It is the
style that the GNU Emacs C mode encourages and which is used in the C
portions of GNU Emacs. (People interested in writing programs for
Project GNU should get a copy of "The GNU Coding Standards", which
also covers semantic and portability issues such as memory usage, the
size of integers, etc.)
The Kernighan & Ritchie style is used throughout their well-known
book "The C Programming Language". It is enabled with the ‘-kr’
option. The Kernighan & Ritchie style corresponds to the following
set of options:
-nbad -bap -bbo -nbc -br -brs -c33 -cd33 -ncdb -ce -ci4 -cli0
-cp33 -cs -d0 -di1 -nfc1 -nfca -hnl -i4 -ip0 -l75 -lp -npcs
-nprs -npsl -saf -sai -saw -nsc -nsob -nss
Kernighan & Ritchie style does not put comments to the right of code
in the same column at all times (nor does it use only one space to
the right of the code), so for this style indent has arbitrarily
chosen column 33.
The style of the original Berkeley indent may be obtained by
specifying ‘-orig’ (or by specifying ‘--original’, using the long
option name). This style is equivalent to the following settings:
-nbad -nbap -bbo -bc -br -brs -c33 -cd33 -cdb -ce -ci4 -cli0
-cp33 -di16 -fc1 -fca -hnl -i4 -ip4 -l75 -lp -npcs -nprs -psl
-saf -sai -saw -sc -nsob -nss -ts8
The Linux style is used in the linux kernel code and drivers. Code
generally has to follow the Linux coding style to be accepted. This
style is equivalent to the following settings:
-nbad -bap -nbc -bbo -hnl -br -brs -c33 -cd33 -ncdb -ce -ci4
-cli0 -d0 -di1 -nfc1 -i8 -ip0 -l80 -lp -npcs -nprs -npsl -sai
-saf -saw -ncs -nsc -sob -nfca -cp33 -ss -ts8 -il1
BLANK LINES top
Various programming styles use blank lines in different places.
indent has a number of options to insert or delete blank lines in
specific places.
The ‘-bad’ option causes indent to force a blank line after every
block of declarations. The ‘-nbad’ option causes indent not to force
such blank lines.
The ‘-bap’ option forces a blank line after every procedure body.
The ‘-nbap’ option forces no such blank line.
The ‘-bbb’ option forces a blank line before every boxed comment (See
COMMENTS.) The ‘-nbbb’ option does not force such blank lines.
The ‘-sob’ option causes indent to swallow optional blank lines (that
is, any optional blank lines present in the input will be removed
from the output). If the ‘-nsob’ is specified, any blank lines
present in the input file will be copied to the output file.
--blank-lines-after-declarations top
The ‘-bad’ option forces a blank line after every block of
declarations. The ‘-nbad’ option does not add any such blank lines.
For example, given the input
char *foo;
char *bar;
/* This separates blocks of declarations. */
int baz;
indent -bad produces
char *foo;
char *bar;
/* This separates blocks of declarations. */
int baz;
and indent -nbad produces
char *foo;
char *bar;
/* This separates blocks of declarations. */
int baz;
--blank-lines-after-procedures top
The ‘-bap’ option forces a blank line after every procedure body.
For example, given the input
int
foo ()
{
puts("Hi");
}
/* The procedure bar is even less interesting. */
char *
bar ()
{
puts("Hello");
}
indent -bap produces
int
foo ()
{
puts ("Hi");
}
/* The procedure bar is even less interesting. */
char *
bar ()
{
puts ("Hello");
}
and indent -nbap produces
int
foo ()
{
puts ("Hi");
}
/* The procedure bar is even less interesting. */
char *
bar ()
{
puts ("Hello");
}
No blank line will be added after the procedure foo.
COMMENTS top
indent formats both C and C++ comments. C comments are begun with
‘/*’, terminated with ‘*/’ and may contain newline characters. C++
comments begin with the delimiter ‘//’ and end at the newline.
indent handles comments differently depending upon their context.
indent attempts to distinguish between comments which follow
statements, comments which follow declarations, comments following
preprocessor directives, and comments which are not preceded by code
of any sort, i.e., they begin the text of the line (although not
necessarily in column 1).
indent further distinguishes between comments found outside of
procedures and aggregates, and those found within them. In
particular, comments beginning a line found within a procedure will
be indented to the column at which code is currently indented. The
exception to this is a comment beginning in the leftmost column;
such a comment is output at that column.
indent attempts to leave boxed comments unmodified. The general idea
of such a comment is that it is enclosed in a rectangle or ‘‘box’’ of
stars or dashes to visually set it apart. More precisely, boxed
comments are defined as those in which the initial ‘/*’ is followed
immediately by the character ‘*’, ‘=’, ‘_’, or ‘-’, or those in which
the beginning comment delimiter (‘/*’) is on a line by itself, and
the following line begins with a ‘*’ in the same column as the star
of the opening delimiter.
Examples of boxed comments are:
/**********************
* Comment in a box!! *
**********************/
/*
* A different kind of scent,
* for a different kind of comment.
*/
indent attempts to leave boxed comments exactly as they are found in
the source file. Thus the indentation of the comment is unchanged,
and its length is not checked in any way. The only alteration made
is that an embedded tab character may be converted into the
appropriate number of spaces.
If the ‘-bbb’ option is specified, all such boxed comments will be
preceded by a blank line, unless such a comment is preceded by code.
Comments which are not boxed comments may be formatted, which means
that the line is broken to fit within a right margin and left-filled
with whitespace. Single newlines are equivalent to a space, but
blank lines (two or more newlines in a row) are taken to mean a
paragraph break. Formatting of comments which begin after the first
column is enabled with the ‘-fca’ option. To format those beginning
in column one, specify ‘-fc1’. Such formatting is disabled by
default.
The right margin for formatting defaults to 78, but may be changed
with the ‘-lc’ option. If the margin specified does not allow the
comment to be printed, the margin will be automatically extended for
the duration of that comment. The margin is not respected if the
comment is not being formatted.
If the ‘-fnc’ option is specified, all comments with ‘/*’ embedded
will have that character sequence replaced by a space followed by the
character ‘*’ thus eliminating nesting.
If the comment begins a line (i.e., there is no program text to its
left), it will be indented to the column it was found in unless the
comment is within a block of code. In that case, such a comment will
be aligned with the indented code of that block (unless the comment
began in the first column). This alignment may be affected by the
‘-d’ option, which specifies an amount by which such comments are
moved to the left, or unindented. For example, ‘-d2’ places comments
two spaces to the left of code. By default, comments are aligned
with code, unless they begin in the first column, in which case they
are left there by default --- to get them aligned with the code,
specify ‘-fc1’.
Comments to the right of code will appear by default in column 33.
This may be changed with one of three options. ‘-c’ will specify the
column for comments following code, ‘-cd’ specifies the column for
comments following declarations, and ‘-cp’ specifies the column for
comments following preprocessor directives #else and #endif. ‘-dj’
together with ‘-cd0’ can be used to suppress alignment of comments to
the right of declarations, causing the comment to follow one tabstop
from the end of the declaration. Normally ‘-cd0’ causes ‘-c’ to
become effective.
If the code to the left of the comment exceeds the beginning column,
the comment column will be extended to the next tabstop column past
the end of the code, or in the case of preprocessor directives, to
one space past the end of the directive. This extension lasts only
for the output of that particular comment.
The ‘-cdb’ option places the comment delimiters on blank lines.
Thus, a single line comment like /* Loving hug */ can be transformed
into:
/*
Loving hug
*/
Stars can be placed at the beginning of multi-line comments with the
‘-sc’ option. Thus, the single-line comment above can be transformed
(with ‘-cdb -sc’) into:
/*
* Loving hug
*/
STATEMENTS top
The ‘-br’ or ‘-bl’ option specifies how to format braces.
The ‘-br’ option formats statement braces like this:
if (x > 0) {
x--;
}
The ‘-bl’ option formats them like this:
if (x > 0)
{
x--;
}
If you use the ‘-bl’ option, you may also want to specify the ‘-bli’
option. This option specifies the number of spaces by which braces
are indented. ‘-bli2’, the default, gives the result shown above.
‘-bli0’ results in the following:
if (x > 0)
{
x--;
}
If you are using the ‘-br’ option, you probably want to also use the
‘-ce’ option. This causes the else in an if-then-else construct to
cuddle up to the immediately preceding ‘}’. For example, with ‘-br
-ce’ you get the following:
if (x > 0) {
x--;
} else {
fprintf (stderr, "...something wrong?\n");
}
With ‘-br -nce’ that code would appear as
if (x > 0) {
x--;
}
else {
fprintf (stderr, "...something wrong?\n");
}
An exception to the behavior occurs when there is a comment between
the right brace and the subsequent else statement. While the ‘-br’
option will cause a left brace to jump over the comment, the else
does not jump over the comment to cuddle because it has a strong
likelihood of changing the meaning of the comment.
The ‘-cdw’ option causes the while in a do-while loop to cuddle up to
the immediately preceding ‘}’. For example, with ‘-cdw’ you get the
following:
do {
x--;
} while (x);
With ‘-ncdw’ that code would appear as
do {
x--;
}
while (x);
The ‘-cli’ option specifies the number of spaces that case labels
should be indented to the right of the containing switch statement.
The default gives code like:
switch (i)
{
case 0:
break;
case 1:
{
++i;
}
default:
break;
}
Using the ‘-cli2’ that would become:
switch (i)
{
case 0:
break;
case 1:
{
++i;
}
default:
break;
}
The indentation of the braces below a case statement can be
controlled with the ‘-cbin’ option. For example, using ‘-cli2 -cbi0’
results in:
switch (i)
{
case 0:
break;
case 1:
{
++i;
}
default:
break;
}
If a semicolon is on the same line as a for or while statement, the
‘-ss’ option will cause a space to be placed before the semicolon.
This emphasizes the semicolon, making it clear that the body of the
for or while statement is an empty statement. ‘-nss’ disables this
feature.
The ‘-pcs’ option causes a space to be placed between the name of the
procedure being called and the ‘(’ (for example, puts ("Hi");. The
‘-npcs’ option would give puts("Hi");).
If the ‘-cs’ option is specified, indent puts a space between a cast
operator and the object to be cast. The ‘-ncs’ ensures that there is
no space between the cast operator and the object. Remember that
indent only knows about the standard C data types and so cannot
recognise user-defined types in casts. Thus (mytype)thing is not
treated as a cast.
The ‘-bs’ option ensures that there is a space between the keyword
sizeof and its argument. In some versions, this is known as the
‘Bill_Shannon’ option.
The ‘-saf’ option forces a space between a for and the following
parenthesis. This is the default.
The ‘-sai’ option forces a space between a if and the following
parenthesis. This is the default.
The ‘-saw’ option forces a space between a while and the following
parenthesis. This is the default.
The ‘-prs’ option causes all parentheses to be separated with a space
from whatever is between them. For example, using ‘-prs’ results in
code like:
while ( ( e_code - s_code ) < ( dec_ind - 1 ) )
{
set_buf_break ( bb_dec_ind );
*e_code++ = ’ ’;
}
DECLARATIONS top
By default indent will line up identifiers, in the column specified
by the ‘-di’ option. For example, ‘-di16’ makes things look like:
int foo;
char *bar;
Using a small value (such as one or two) for the ‘-di’ option can be
used to cause the identifiers to be placed in the first available
position; for example:
int foo;
char *bar;
The value given to the ‘-di’ option will still affect variables which
are put on separate lines from their types, for example ‘-di2’ will
lead to:
int
foo;
If the ‘-bc’ option is specified, a newline is forced after each
comma in a declaration. For example,
int a,
b,
c;
With the ‘-nbc’ option this would look like
int a, b, c;
The ‘-bfda’ option causes a newline to be forced after the comma
separating the arguments of a function declaration. The arguments
will appear at one indention level deeper than the function
declaration. This is particularly helpful for functions with long
argument lists. The option ‘-bfde’ causes a newline to be forced
before the closing bracket of the function declaration. For both
options the ’n’ setting is the default: -nbdfa and -nbdfe.
For example,
void foo (int arg1, char arg2, int *arg3, long arg4, char arg5);
With the ‘-bfda’ option this would look like
void foo (
int arg1,
char arg2,
int *arg3,
long arg4,
char arg5);
With, in addition, the ‘-bfde’ option this would look like
void foo (
int arg1,
char arg2,
int *arg3,
long arg4,
char arg5
);
The ‘-psl’ option causes the type of a procedure being defined to be
placed on the line before the name of the procedure. This style is
required for the etags program to work correctly, as well as some of
the c-mode functions of Emacs.
You must use the ‘-T’ option to tell indent the name of all the
typenames in your program that are defined by typedef. ‘-T’ can be
specified more than once, and all names specified are used. For
example, if your program contains
typedef unsigned long CODE_ADDR;
typedef enum {red, blue, green} COLOR;
you would use the options ‘-T CODE_ADDR -T COLOR’.
The ‘-brs’ or ‘-bls’ option specifies how to format braces in struct
declarations. The ‘-brs’ option formats braces like this:
struct foo {
int x;
};
The ‘-bls’ option formats them like this:
struct foo
{
int x;
};
Similarly to the structure brace ‘-brs’ and ‘-bls’ options,
the function brace options ‘-brf’ or ‘-blf’ specify how to format
the braces in function definitions. The ‘-brf’ option formats braces
like this:
int one(void) {
return 1;
};
The ‘-blf’ option formats them like this:
int one(void)
{
return 1;
};
INDENTATION top
One issue in the formatting of code is how far each line should be
indented from the left margin. When the beginning of a statement
such as if or for is encountered, the indentation level is increased
by the value specified by the ‘-i’ option. For example, use ‘-i8’ to
specify an eight character indentation for each level. When a
statement is broken across two lines, the second line is indented by
a number of additional spaces specified by the ‘-ci’ option. ‘-ci’
defaults to 0. However, if the ‘-lp’ option is specified, and a line
has a left parenthesis which is not closed on that line, then
continuation lines will be lined up to start at the character
position just after the left parenthesis. This processing also
applies to ‘[’ and applies to ‘{’ when it occurs in initialization
lists. For example, a piece of continued code might look like this
with ‘-nlp -ci3’ in effect:
p1 = first_procedure (second_procedure (p2, p3),
third_procedure (p4, p5));
With ‘-lp’ in effect the code looks somewhat clearer:
p1 = first_procedure (second_procedure (p2, p3),
third_procedure (p4, p5));
When a statement is broken in between two or more paren pairs (...),
each extra pair causes the indentation level extra indentation:
if ((((i < 2 &&
k > 0) || p == 0) &&
q == 1) ||
n = 0)
The option ‘-ipN’ can be used to set the extra offset per paren. For
instance, ‘-ip0’ would format the above as:
if ((((i < 2 &&
k > 0) || p == 0) &&
q == 1) ||
n = 0)
indent assumes that tabs are placed at regular intervals of both
input and output character streams. These intervals are by default 8
columns wide, but (as of version 1.2) may be changed by the ‘-ts’
option. Tabs are treated as the equivalent number of spaces.
The indentation of type declarations in old-style function
definitions is controlled by the ‘-ip’ parameter. This is a numeric
parameter specifying how many spaces to indent type declarations.
For example, the default ‘-ip5’ makes definitions look like this:
char *
create_world (x, y, scale)
int x;
int y;
float scale;
{
. . .
}
For compatibility with other versions of indent, the option ‘-nip’ is
provided, which is equivalent to ‘-ip0’.
ANSI C allows white space to be placed on preprocessor command lines
between the character ‘#’ and the command name. By default, indent
removes this space, but specifying the ‘-lps’ option directs indent
to leave this space unmodified. The option ‘-ppi’ overrides ‘-nlps’
and ‘-lps’.
This option can be used to request that preprocessor conditional
statements can be indented by to given number of spaces, for example
with the option ‘-ppi 3’
#if X
#if Y
#define Z 1
#else
#define Z 0
#endif
#endif
becomes
#if X
# if Y
# define Z 1
# else
# define Z 0
# endif
#endif
This option sets the offset at which a label (except case labels)
will be positioned. If it is set to zero or a positive number, this
indicates how far from the left margin to indent a label. If it is
set to a negative number, this indicates how far back from the
current indent level to place the label. The default setting is -2
which matches the behaviour of earlier versions of indent. Note that
this parameter does not affect the placing of case labels; see the
‘-cli’ parameter for that. For example with the option ‘-il 1’
group
function()
{
if (do_stuff1() == ERROR)
goto cleanup1;
if (do_stuff2() == ERROR)
goto cleanup2;
return SUCCESS;
cleanup2:
do_cleanup2();
cleanup1:
do_cleanup1();
return ERROR;
}
becomes
group
function()
{
if (do_stuff1() == ERROR)
goto cleanup1;
if (do_stuff2() == ERROR)
goto cleanup2;
return SUCCESS;
cleanup2:
do_cleanup2();
cleanup1:
do_cleanup1();
return ERROR;
}
BREAKING LONG LINES top
With the option ‘-ln’, or ‘--line-lengthn’, it is possible to specify
the maximum length of a line of C code, not including possible
comments that follow it.
When lines become longer than the specified line length, GNU indent
tries to break the line at a logical place. This is new as of
version 2.1 however and not very intelligent or flexible yet.
Currently there are three options that allow one to interfere with
the algorithm that determines where to break a line.
The ‘-bbo’ option causes GNU indent to prefer to break long lines
before the boolean operators && and ||. The ‘-nbbo’ option causes
GNU indent not have that preference. For example, the default option
‘-bbo’ (together with ‘--line-length60’ and ‘--ignore-newlines’)
makes code look like this:
if (mask
&& ((mask[0] == ’\0’)
|| (mask[1] == ’\0’
&& ((mask[0] == ’0’) || (mask[0] == ’*’)))))
Using the option ‘-nbbo’ will make it look like this:
if (mask &&
((mask[0] == ’\0’) ||
(mask[1] == ’\0’ &&
((mask[0] == ’0’) || (mask[0] == ’*’)))))
The default ‘-hnl’, however, honours newlines in the input file by
giving them the highest possible priority to break lines at. For
example, when the input file looks like this:
if (mask
&& ((mask[0] == ’\0’)
|| (mask[1] == ’\0’ && ((mask[0] == ’0’) || (mask[0] == ’*’)))))
then using the option ‘-hnl’, or ‘--honour-newlines’, together with
the previously mentioned ‘-nbbo’ and ‘--line-length60’, will cause
the output not to be what is given in the last example but instead
will prefer to break at the positions where the code was broken in
the input file:
if (mask
&& ((mask[0] == ’\0’)
|| (mask[1] == ’\0’ &&
((mask[0] == ’0’) || (mask[0] == ’*’)))))
The idea behind this option is that lines which are too long, but are
already broken up, will not be touched by GNU indent. Really messy
code should be run through indent at least once using the ‘--ignore-
newlines’ option though.
The ‘-gts’ option affects how the gettext standard macros _() and
N_() are treated. The default behavior (or the use of ‘-ngts’)
causes indent to treat them as it does other functions, so that a
long string is broken like the following example.
if (mask)
{
warning (_
("This is a long string that stays together."));
}
With the ‘-gts’ option, the underscore is treated as a part of the
string, keeping it tied to the string, and respecting the fact that
gettext is unobtrusively providing a localized string. This only
works if _(" is together as a unit at the beginning of the string and
") is together as a unit at the end.
if (mask)
{
warning
(_("This is a long string that stays together."));
}
DISABLING FORMATTING top
Formatting of C code may be disabled for portions of a program by
embedding special control comments in the program. To turn off
formatting for a section of a program, place the disabling control
comment /* *INDENT-OFF* */ on a line by itself just before that
section. Program text scanned after this control comment is output
precisely as input with no modifications until the corresponding
enabling comment is scanned on a line by itself. The disabling
control comment is /* *INDENT-ON* */, and any text following the
comment on the line is also output unformatted. Formatting begins
again with the input line following the enabling control comment.
More precisely, indent does not attempt to verify the closing
delimiter (*/) for these C comments, and any whitespace on the line
is totally transparent.
These control comments also function in their C++ formats, namely //
*INDENT-OFF* and // *INDENT-ON*.
It should be noted that the internal state of indent remains
unchanged over the course of the unformatted section. Thus, for
example, turning off formatting in the middle of a function and
continuing it after the end of the function may lead to bizarre
results. It is therefore wise to be somewhat modular in selecting
code to be left unformatted.
As a historical note, some earlier versions of indent produced error
messages beginning with *INDENT**. These versions of indent were
written to ignore any input text lines which began with such error
messages. I have removed this incestuous feature from GNU indent.
MISCELLANEOUS OPTIONS top
To find out what version of indent you have, use the command indent
-version. This will report the version number of indent, without
doing any of the normal processing.
The ‘-v’ option can be used to turn on verbose mode. When in verbose
mode, indent reports when it splits one line of input into two more
more lines of output, and gives some size statistics at completion.
The ‘-pmt’ option causes indent to preserve the access and
modification times on the output files. Using this option has the
advantage that running indent on all source and header files in a
project won’t cause make to rebuild all targets. This option is only
available on Operating Systems that have the POSIX utime(2) function.
Please report any bugs to bug-indent@gnu.org.
When indent is run twice on a file, with the same profile, it should
never change that file the second time. With the current design of
indent, this can not be guaranteed, and it has not been extensively
tested.
indent does not understand C. In some cases this leads to the
inability to join lines. The result is that running a file through
indent is irreversible, even if the used input file was the result of
running indent with a given profile (‘.indent.pro’).
While an attempt was made to get indent working for C++, it will not
do a good job on any C++ source except the very simplest.
indent does not look at the given ‘--line-length’ option when writing
comments to the output file. This results often in comments being
put far to the right. In order to prohibit indent from joining a
broken line that has a comment at the end, make sure that the
comments start on the first line of the break.
indent does not count lines and comments (see the ‘-v’ option) when
indent is turned off with /* *INDENT-OFF* */.
Comments of the form /*UPPERCASE*/ are not treated as comment but as
an identifier, causing them to be joined with the next line. This
renders comments of this type useless, unless they are embedded in
the code to begin with.
COPYRIGHT top
The following copyright notice applies to the indent program. The
copyright and copying permissions for this manual appear near the
beginning of ‘indent.texinfo’ and ‘indent.info’, and near the end of
‘indent.1’.
Copyright (c) 2001 David Ingamells.
Copyright (c) 1999 Carlo Wood.
Copyright (c) 1995, 1996 Joseph Arceneaux.
Copyright (c) 1989, 1992, 1993, 1994, 1995, 1996, 2014 Free Software Foundation
Copyright (c) 1985 Sun Microsystems, Inc.
Copyright (c) 1980 The Regents of the University of California.
Copyright (c) 1976 Board of Trustees of the University of Illinois.
All rights reserved.
Redistribution and use in source and binary forms are permitted
provided that the above copyright notice and this paragraph are
duplicated in all such forms and that any documentation,
advertising materials, and other materials related to such
distribution and use acknowledge that the software was developed
by the University of California, Berkeley, the University of Illinois,
Urbana, and Sun Microsystems, Inc. The name of either University
or Sun Microsystems may not be used to endorse or promote products
derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED ‘‘AS IS’’ AND WITHOUT ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
PURPOSE.
Options’ Cross Key top
Here is a list of options alphabetized by long option, to help you
find the corresponding short option.
--blank-lines-after-commas -bc
--blank-lines-after-declarations -bad
--blank-lines-after-procedures -bap
--blank-lines-before-block-comments -bbb
--braces-after-if-line -bl
--braces-after-func-def-line -blf
--brace-indent -bli
--braces-after-struct-decl-line -bls
--braces-on-if-line -br
--braces-on-func-def-line -brf
--braces-on-struct-decl-line -brs
--break-after-boolean-operator -nbbo
--break-before-boolean-operator -bbo
--break-function-decl-args -bfda
--break-function-decl-args-end -bfde
--case-indentation -clin
--case-brace-indentation -cbin
--comment-delimiters-on-blank-lines -cdb
--comment-indentation -cn
--continuation-indentation -cin
--continue-at-parentheses -lp
--cuddle-do-while -cdw
--cuddle-else -ce
--declaration-comment-column -cdn
--declaration-indentation -din
--dont-break-function-decl-args -nbfda
--dont-break-function-decl-args-end -nbfde
--dont-break-procedure-type -npsl
--dont-cuddle-do-while -ncdw
--dont-cuddle-else -nce
--dont-format-comments -nfca
--dont-format-first-column-comments -nfc1
--dont-line-up-parentheses -nlp
--dont-left-justify-declarations -ndj
--dont-space-special-semicolon -nss
--dont-star-comments -nsc
--else-endif-column -cpn
--format-all-comments -fca
--format-first-column-comments -fc1
--gnu-style -gnu
--honour-newlines -hnl
--ignore-newlines -nhnl
--ignore-profile -npro
--indent-label -iln
--indent-level -in
--k-and-r-style -kr
--leave-optional-blank-lines -nsob
--leave-preprocessor-space -lps
--left-justify-declarations -dj
--line-comments-indentation -dn
--line-length -ln
--linux-style -linux
--no-blank-lines-after-commas -nbc
--no-blank-lines-after-declarations -nbad
--no-blank-lines-after-procedures -nbap
--no-blank-lines-before-block-comments -nbbb
--no-comment-delimiters-on-blank-lines -ncdb
--no-space-after-casts -ncs
--no-parameter-indentation -nip
--no-space-after-for -nsaf
--no-space-after-function-call-names -npcs
--no-space-after-if -nsai
--no-space-after-parentheses -nprs
--no-space-after-while -nsaw
--no-tabs -nut
--no-verbosity -nv
--original -orig
--parameter-indentation -ipn
--paren-indentation -pin
--preserve-mtime -pmt
--preprocessor-indentation -ppin
--procnames-start-lines -psl
--space-after-cast -cs
--space-after-for -saf
--space-after-if -sai
--space-after-parentheses -prs
--space-after-procedure-calls -pcs
--space-after-while -saw
--space-special-semicolon -ss
--standard-output -st
--start-left-side-of-comments -sc
--struct-brace-indentation -sbin
--swallow-optional-blank-lines -sob
--tab-size -tsn
--use-tabs -ut
--verbose -v
RETURN VALUE top
Unknown
$HOME/.indent.pro holds default options for indent.
AUTHORS top
Carlo Wood
Joseph Arceneaux
Jim Kingdon
David Ingamells
HISTORY top
Derived from the UCB program "indent".
COPYING top
Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 2014 Free Software
Foundation, Inc. Copyright (C) 1995, 1996 Joseph Arceneaux.
Copyright (C) 1999 Carlo Wood. Copyright (C) 2001 David Ingamells.
Copyright (C) 2013 Łukasz Stelmach.
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.
COLOPHON top
This page is part of the GNU indent (a C program formatter) project.
Information about the project can be found at
⟨http://www.gnu.org/software/indent/⟩. If you have a bug report for
this manual page, send it to bug-indent@gnu.org. This page was
obtained from the project's upstream Mercurial repository
⟨http://hg.savannah.gnu.org/hgweb/indent/⟩ on 2017-07-05. If you dis‐
cover any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page, or
you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org