CUT
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
PROLOG
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.
NAME
cut — cut out selected fields of each line of a file
SYNOPSIS
cut -b list [-n] [file…]
cut -c list [file…]
cut -f list [-d delim] [-s] [file…]
DESCRIPTION
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.
OPTIONS
The cut utility shall conform to the Base Definitions volume of POSIX.1-2017, Section 12.2, Utility Syntax Guidelines.
The application shall ensure that the option-argument list (see options −b, −c, and −f below) is a
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. |
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−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. |
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−d delim |
Set the field delimiter to the character delim. The default is the |
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−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. |
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−n |
Do not split characters. When specified with the −b option, each element in list of the form low−high ( |
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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
−s |
Suppress lines with no delimiter characters, when used with the −f option. Unless specified, lines with no delimiters shall be passed through untouched. |
OPERANDS
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. |
STDIN
The standard input shall be used only if no file operands are specified, or if a file operand is ’−’. See the INPUT FILES section.
INPUT FILES
The input files shall be text files, except that line lengths shall be unlimited.
ENVIRONMENT VARIABLES
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.1-2017, Section 8.2, Internationalization Variables for the precedence of internationalization variables used to determine the values of locale categories.) |
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LC_ALL |
If set to a non-empty string value, override the values of all the other internationalization variables. |
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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. |
ASYNCHRONOUS EVENTS
Default.
STDOUT
The cut utility output shall be a concatenation of the selected bytes, characters, or fields (one of the following):
“%sn”, <concatenation of bytes>
“%sn”, <concatenation of characters>
“%sn”, <concatenation of fields and field delimiters>
STDERR
The standard error shall be used only for diagnostic messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 |
All input files were output successfully. |
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>0 |
An error occurred. |
CONSEQUENCES OF ERRORS
Default.
The following sections are informative.
APPLICATION USAGE
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
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
EXAMPLES
Examples of the option qualifier list:
1,4,7 |
Select the first, fourth, and seventh bytes, characters, or fields and field delimiters. |
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1−3,8 |
Equivalent to 1,2,3,8. |
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−5,10 |
Equivalent to 1,2,3,4,5,10. |
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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.1-2017 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
paste -d “