CUT(1) General Commands Manual CUT(1)

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 utility argument syntax guidelines described in 2.10.2. The option-argument list (see options −b, −c, and −f below) shall be a commaseparated 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. The following options shall be supported by the implementation:

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.

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.

delim

Set the field delimiter to the character delim. The default is the <tab> character.

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.

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 the number of bytes in the current line, not including the terminating <newline> character. 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.

Suppress lines with no delimiter characters, when used with the

option. Unless specified, lines with no delimiters shall be passed through untouched.

The following operands shall be supported by the implementation:

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 Input Files.

The input files shall be text files, except that line lengths shall be unlimited.

The following environment variables shall affect the execution of cut:

This variable shall determine the locale to use for the locale categories when both LC_ALL and the corresponding environment variable (beginning with LC_ ) do not specify a locale. See 2.6.

This variable shall determine the locale to be used to override any values for locale categories specified by the settings of LANG or any environment variables beginning with LC_.

This variable shall determine the locale for the interpretation of sequences of bytes of text data as characters (e.g., single- versus multibyte characters in arguments and input files).

This variable shall determine the language in which messages should be written.

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>

Used only for diagnostic messages.

None.

None.

The cut utility shall exit with one of the following values:

All input files were output successfully.

An error occurred.

Default.

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 through last. The low−high forms are not always equivalent when used with −b and −n and multibyte 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 standard 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> character and file2 that contains the remainder of the data from file. (Note that file2 will not be a text file if there are lines in file that are longer than 500 + 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 standard, 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 make sense together has been deliberately left unspecified in favor of global wording in Section 2. The traditional cut utility has worked in an environment where bytes and characters were equivalent (modulo <backspace> and <tab> processing in some implementations). In the extended world of multibyte 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 will end up with all the characters in file appearing exactly once in file1 or file2. (There is, however, a <newline> character in both file1 and file2 for each <newline> character in file.)

September 1991 posix.fail