cut(1)

NAME

cut — cut out (extract) selected fields of each line of a file

SYNOPSIS

cut -c list [file]...

cut -b list [-n] [file]...

cut -f list [-d char] [-s] [file]...

DESCRIPTION

cut cuts out (extracts) columns from a table or fields from each line in a file; in data base parlance, it implements the projection of a relation. Fields as specified by list can be fixed length (defined in terms of character or byte position in a line when using the -c or -b option), or the length can vary from line to line and be marked with a field delimiter character such as the tab character (when using the -f option). cut can be used as a filter; if no files are given, the standard input is used.

When processing single-byte character sets, the -c and -b options are equivalent and produce identical results. When processing multi-byte character sets, when the -b and -n options are used together, their combined behavior is very similar, but not identical to the -c option.

Options

Options are interpreted as follows:

list

A comma-separated list of integer byte (-b option), character (-c option), or field (-f option) numbers, in increasing order, with optional - to indicate ranges. For example:

1,4,7: Positions 1, 4, and 7.
1-3,8: Positions 1 through 3 and 8.
-5,10: Positions 1 through 5 and 10.
3-: Position 3 through last position.

-b list

Cut based on a list of bytes. Each selected byte is output unless the -n option is also specified.

-c list

Cut based on character positions specified by list (-c 1-72 extracts the first 72 characters of each line).

-f list

Where list is a list of fields assumed to be separated in the file by a delimiter character (see -d); for example, -f 1,7 copies the first and seventh field only. Lines with no field delimiters will be passed through intact (useful for table subheadings), unless -s is specified.

-d char

The character following -d is the field delimiter (-f option only). Default is tab. Space or other characters with special meaning to the shell must be quoted. Adjacent field delimiters delimit null fields. char may be an international code set character.

-n

Do not split characters. If the high end of a range within a list is not the last byte of a character, that character is not included in the output. However, if the low end of a range within a list is not the first byte of a character, the entire character is included in the output."

-s

Suppresses lines with no delimiter characters when using -f option. Unless -s is specified, lines with no delimiters appear in the output without alteration.

Hints

Use grep to extract text from a file based on text pattern recognition (using regular expressions). Use paste to merge files line-by-line in columnar format. To rearrange columns in a table in a different sequence, use cut and paste. See grep(1) and paste(1) for more information.

EXTERNAL INFLUENCES

Environment Variables

LC_CTYPE determines the interpretation of text as single and/or multi-byte characters.

If LC_CTYPE is not specified in the environment or is set to the empty string, the value of LANG is used as a default for each unspecified or empty variable. If LANG is not specified or is set to the empty string, a default of "C" (see lang(5)) is used instead of LANG. If any internationalization variable contains an invalid setting, cut behaves as if all internationalization variables are set to "C". See environ(5).

International Code Set Support

cut supports both single- and multi-byte character code sets. International code set characters may be specified in the char given to the -d option. cut recognizes the international code set characters according to the locale specified in the LC_CTYPE environment variable.

EXAMPLES

Password file mapping of user ID to user names:

cut -d : -f 1,5 /etc/passwd 

Set environment variable name to current login name:

name=`who am i | cut -f 1 -d " "`

Convert file source containing lines of arbitrary length into two files where file1 contains the first 500 bytes (unless the 500th byte is within a multi-byte character), and file2 contains the remainder of each line:

cut -b 1-500 -n source > file1 
cut -b 500- -n source > file2 

DIAGNOSTICS

line too long: Line length must not exceed LINE_MAX characters or fields, including the new-line character (see limits(5).
bad list for b/c/f option: Missing -b, -c, or -f option or incorrectly specified list. No error occurs if a line has fewer fields than the list calls for.
no fields: list is empty.

WARNINGS

cut does not expand tabs. Pipe text through expand(1) if tab expansion is required.

Backspace characters are treated the same as any other character. To eliminate backspace characters before processing by cut, use the fold or col command (see fold(1) and col(1)).

AUTHOR

cut was developed by OSF and HP.

STANDARDS CONFORMANCE

cut: SVID2, SVID3, XPG2, XPG3, XPG4, POSIX.2