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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 |
CUT(1P) POSIX Programmer's Manual CUT(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.
cut — cut out selected fields of each line of a file
cut −b list [−n] [file...]
cut −c list [file...]
cut −f list [−d delim] [−s] [file...]
The cut utility shall cut out bytes (−b option), characters (−c
option), or character-delimited fields (−f option) from each line in
one or more files, concatenate them, and write them to standard
output.
The cut utility shall conform to the Base Definitions volume of
POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines.
The application shall ensure that the option-argument list (see
options −b, −c, and −f below) is a <comma>-separated list or
<blank>-separated list of positive numbers and ranges. Ranges can be
in three forms. The first is two positive numbers separated by a
<hyphen> (low−high), which represents all fields from the first
number to the second number. The second is a positive number preceded
by a <hyphen> (−high), which represents all fields from field number
1 to that number. The third is a positive number followed by a
<hyphen> (low−), which represents that number to the last field,
inclusive. The elements in list can be repeated, can overlap, and can
be specified in any order, but the bytes, characters, or fields
selected shall be written in the order of the input data. If an
element appears in the selection list more than once, it shall be
written exactly once.
The following options shall be supported:
−b list Cut based on a list of bytes. Each selected byte shall be
output unless the −n option is also specified. It shall not
be an error to select bytes not present in the input line.
−c list Cut based on a list of characters. Each selected character
shall be output. It shall not be an error to select
characters not present in the input line.
−d delim Set the field delimiter to the character delim. The
default is the <tab>.
−f list Cut based on a list of fields, assumed to be separated in
the file by a delimiter character (see −d). Each selected
field shall be output. Output fields shall be separated by
a single occurrence of the field delimiter character. Lines
with no field delimiters shall be passed through intact,
unless −s is specified. It shall not be an error to select
fields not present in the input line.
−n Do not split characters. When specified with the −b option,
each element in list of the form low−high
(<hyphen>-separated numbers) shall be modified as follows:
* If the byte selected by low is not the first byte of a
character, low shall be decremented to select the first
byte of the character originally selected by low. If
the byte selected by high is not the last byte of a
character, high shall be decremented to select the last
byte of the character prior to the character originally
selected by high, or zero if there is no prior
character. If the resulting range element has high
equal to zero or low greater than high, the list
element shall be dropped from list for that input line
without causing an error.
Each element in list of the form low− shall be treated as
above with high set to the number of bytes in the current
line, not including the terminating <newline>. Each
element in list of the form −high shall be treated as above
with low set to 1. Each element in list of the form num (a
single number) shall be treated as above with low set to
num and high set to num.
−s Suppress lines with no delimiter characters, when used with
the −f option. Unless specified, lines with no delimiters
shall be passed through untouched.
The following operand shall be supported:
file A pathname of an input file. If no file operands are
specified, or if a file operand is '−', the standard input
shall be used.
The standard input shall be used only if no file operands are
specified, or if a file operand is '−'. See the INPUT FILES section.
The input files shall be text files, except that line lengths shall
be unlimited.
The following environment variables shall affect the execution of
cut:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base Definitions
volume of POSIX.1‐2008, Section 8.2, Internationalization
Variables for the precedence of internationalization
variables used to determine the values of locale
categories.)
LC_ALL If set to a non-empty string value, override the values of
all the other internationalization variables.
LC_CTYPE Determine the locale for the interpretation of sequences of
bytes of text data as characters (for example, single-byte
as opposed to multi-byte characters in arguments and input
files).
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
Default.
The cut utility output shall be a concatenation of the selected
bytes, characters, or fields (one of the following):
"%s\n", <concatenation of bytes>
"%s\n", <concatenation of characters>
"%s\n", <concatenation of fields and field delimiters>
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 All input files were output successfully.
>0 An error occurred.
Default.
The following sections are informative.
The cut and fold utilities can be used to create text files out of
files with arbitrary line lengths. The cut utility should be used
when the number of lines (or records) needs to remain constant. The
fold utility should be used when the contents of long lines need to
be kept contiguous.
Earlier versions of the cut utility worked in an environment where
bytes and characters were considered equivalent (modulo <backspace>
and <tab> processing in some implementations). In the extended world
of multi-byte characters, the new −b option has been added. The −n
option (used with −b) allows it to be used to act on bytes rounded to
character boundaries. The algorithm specified for −n guarantees
that:
cut −b 1−500 −n file > file1
cut −b 501− −n file > file2
ends up with all the characters in file appearing exactly once in
file1 or file2. (There is, however, a <newline> in both file1 and
file2 for each <newline> in file.)
Examples of the option qualifier list:
1,4,7 Select the first, fourth, and seventh bytes, characters, or
fields and field delimiters.
1−3,8 Equivalent to 1,2,3,8.
−5,10 Equivalent to 1,2,3,4,5,10.
3− Equivalent to third to last, inclusive.
The low−high forms are not always equivalent when used with −b and −n
and multi-byte characters; see the description of −n.
The following command:
cut −d : −f 1,6 /etc/passwd
reads the System V password file (user database) and produces lines
of the form:
<user ID>:<home directory>
Most utilities in this volume of POSIX.1‐2008 work on text files. The
cut utility can be used to turn files with arbitrary line lengths
into a set of text files containing the same data. The paste utility
can be used to create (or recreate) files with arbitrary line
lengths. For example, if file contains long lines:
cut −b 1−500 −n file > file1
cut −b 501− −n file > file2
creates file1 (a text file) with lines no longer than 500 bytes (plus
the <newline>) and file2 that contains the remainder of the data from
file. (Note that file2 is not a text file if there are lines in file
that are longer than 500 + {LINE_MAX} bytes.) The original file can
be recreated from file1 and file2 using the command:
paste −d "\0" file1 file2 > file
Some historical implementations do not count <backspace> characters
in determining character counts with the −c option. This may be
useful for using cut for processing nroff output. It was deliberately
decided not to have the −c option treat either <backspace> or <tab>
characters in any special fashion. The fold utility does treat these
characters specially.
Unlike other utilities, some historical implementations of cut exit
after not finding an input file, rather than continuing to process
the remaining file operands. This behavior is prohibited by this
volume of POSIX.1‐2008, where only the exit status is affected by
this problem.
The behavior of cut when provided with either mutually-exclusive
options or options that do not work logically together has been
deliberately left unspecified in favor of global wording in Section
1.4, Utility Description Defaults.
The OPTIONS section was changed in response to IEEE PASC
Interpretation 1003.2 #149. The change represents historical practice
on all known systems. The original standard was ambiguous on the
nature of the output.
The list option-arguments are historically used to select the
portions of the line to be written, but do not affect the order of
the data. For example:
echo abcdefghi | cut −c6,2,4−7,1
yields "abdefg".
A proposal to enhance cut with the following option:
−o Preserve the selected field order. When this option is
specified, each byte, character, or field (or ranges of such)
shall be written in the order specified by the list option-
argument, even if this requires multiple outputs of the same
bytes, characters, or fields.
was rejected because this type of enhancement is outside the scope of
the IEEE P1003.2b draft standard.
None.
Section 2.5, Parameters and Variables, fold(1p), grep(1p), paste(1p)
The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
Variables, 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 CUT(1P)
Pages that refer to this page: fold(1p), paste(1p)