8. Operating on fields within a line

8.1 cut: Print selected parts of lines		Print selected parts of lines.
8.2 paste: Merge lines of files		Merge lines of files.
8.3 join: Join lines on a common field		Join lines on a common field.

8.1 cut: Print selected parts of lines

cut writes to standard output selected parts of each line of each input file, or standard input if no files are given or for a file name of `-'. Synopsis:

cut [option]... [file]...

In the table which follows, the byte-list, character-list, and field-list are one or more numbers or ranges (two numbers separated by a dash) separated by commas. Bytes, characters, and fields are numbered from starting at 1. Incomplete ranges may be given: `-m' means `1-m'; `n-' means `n' through end of line or last field.

The program accepts the following options. Also see 2. Common options.

`-b byte-list'

`--bytes=byte-list'

Print only the bytes in positions listed in byte-list. Tabs and backspaces are treated like any other character; they take up 1 byte.

`-c character-list'

`--characters=character-list'

Print only characters in positions listed in character-list. The same as `-b' for now, but internationalization will change that. Tabs and backspaces are treated like any other character; they take up 1 character.

`-f field-list'

`--fields=field-list'

Print only the fields listed in field-list. Fields are separated by a TAB character by default.

`-d input_delim_byte'

`--delimiter=input_delim_byte'

For `-f', fields are separated in the input by the first character in input_delim_byte (default is TAB).

`-n'

Do not split multi-byte characters (no-op for now).

`-s'

`--only-delimited'

For `-f', do not print lines that do not contain the field separator character.

`--output-delimiter=output_delim_string'

For `-f', output fields are separated by output_delim_string The default is to use the input delimiter.

8.2 paste: Merge lines of files

paste writes to standard output lines consisting of sequentially corresponding lines of each given file, separated by a TAB character. Standard input is used for a file name of `-' or if no input files are given.

Synopsis:

paste [option]... [file]...

The program accepts the following options. Also see 2. Common options.

`-s'

`--serial'

Paste the lines of one file at a time rather than one line from each file.

`-d delim-list'

`--delimiters delim-list'

Consecutively use the characters in delim-list instead of TAB to separate merged lines. When delim-list is exhausted, start again at its beginning.

8.3 join: Join lines on a common field

join writes to standard output a line for each pair of input lines that have identical join fields. Synopsis:

join [option]... file1 file2

Either file1 or file2 (but not both) can be `-', meaning standard input. file1 and file2 should be already sorted in increasing textual order on the join fields, using the collating sequence specified by the LC_COLLATE locale. Unless the `-t' option is given, the input should be sorted ignoring blanks at the start of the join field, as in sort -b. If the `--ignore-case' option is given, lines should be sorted without regard to the case of characters in the join field, as in sort -f.

The defaults are: the join field is the first field in each line; fields in the input are separated by one or more blanks, with leading blanks on the line ignored; fields in the output are separated by a space; each output line consists of the join field, the remaining fields from file1, then the remaining fields from file2.

The program accepts the following options. Also see 2. Common options.

`-a file-number'

Print a line for each unpairable line in file file-number (either `1' or `2'), in addition to the normal output.

`-e string'

Replace those output fields that are missing in the input with string.

`-i'

`--ignore-case'

Ignore differences in case when comparing keys. With this option, the lines of the input files must be ordered in the same way. Use `sort -f' to produce this ordering.

`-1 field'

`-j1 field'

Join on field field (a positive integer) of file 1.

`-2 field'

`-j2 field'

Join on field field (a positive integer) of file 2.

`-j field'

Equivalent to `-1 field -2 field'.

`-o field-list...'

Construct each output line according to the format in field-list. Each element in field-list is either the single character `0' or has the form m.n where the file number, m, is `1' or `2' and n is a positive field number.

A field specification of `0' denotes the join field. In most cases, the functionality of the `0' field spec may be reproduced using the explicit m.n that corresponds to the join field. However, when printing unpairable lines (using either of the `-a' or `-v' options), there is no way to specify the join field using m.n in field-list if there are unpairable lines in both files. To give join that functionality, POSIX invented the `0' field specification notation.

The elements in field-list are separated by commas or blanks. Multiple field-list arguments can be given after a single `-o' option; the values of all lists given with `-o' are concatenated together. All output lines -- including those printed because of any -a or -v option -- are subject to the specified field-list.

`-t char'

Use character char as the input and output field separator.

`-v file-number'

Print a line for each unpairable line in file file-number (either `1' or `2'), instead of the normal output.

In addition, when GNU join is invoked with exactly one argument, options `--help' and `--version' are recognized. See section 2. Common options.