The Open Group Base Specifications Issue 7
IEEE Std 1003.1-2008, 2016 Edition
Copyright © 2001-2016 The IEEE and The Open Group

#### NAME

> paste - merge corresponding or subsequent lines of files

#### SYNOPSIS

> ``paste` [`-s`] [`-d` list] file`...``

#### DESCRIPTION

> The paste utility shall concatenate the corresponding lines of the given input files, and write the resulting lines to standard output.

> The default operation of paste shall concatenate the corresponding lines of the input files. The <newline> of every line except the line from the last input file shall be replaced with a <tab>.

> If an end-of-file condition is detected on one or more input files, but not all input files, paste shall behave as though empty lines were read from the files on which end-of-file was detected, unless the -s option is specified.

#### OPTIONS

> The paste utility shall conform to XBD Utility Syntax Guidelines.

> The following options shall be supported:

> -d list
>   Unless a <backslash> character appears in list, each character in list is an element specifying a delimiter character. If a <backslash> character appears in list, the <backslash> character and one or more characters following it are an element specifying a delimiter character as described below. These elements specify one or more delimiters to use, instead of the default <tab>, to replace the <newline> of the input lines. The elements in list shall be used circularly; that is, when the list is exhausted the first element from the list is reused. When the -s option is specified:

>   - The last <newline> in a file shall not be modified.

>   - The delimiter shall be reset to the first element of list after each file operand is processed.

>   When the -s option is not specified:

>   - The <newline> characters in the file specified by the last file operand shall not be modified.

>   - The delimiter shall be reset to the first element of list each time a line is processed from each file.

>   If a <backslash> character appears in list, it and the character following it shall be used to represent the following delimiter characters:

>   `\n`
>     <newline>.
>   `\t`
>     <tab>.
>   `\\`
>     <backslash> character.
>   `\0`
>     Empty string (not a null character). If `'\0'` is immediately followed by the character `'x'`, the character `'X'`, or any character defined by the LC_CTYPE digit keyword (see XBD Locale), the results are unspecified.

>   If any other characters follow the <backslash>, the results are unspecified.

> -s
>   Concatenate all of the lines from each input file into one line of output per file, in command line order. The <newline> of every line except the last line in each input file shall be replaced with a <tab>, unless otherwise specified by the -d option. If an input file is empty, the output line corresponding to that file shall consist of only a <newline> character.

#### OPERANDS

> The following operand shall be supported:

> file
>   A pathname of an input file. If `'-'` is specified for one or more of the files, the standard input shall be used; the standard input shall be read one line at a time, circularly, for each instance of `'-'`. Implementations shall support pasting of at least 12 file operands.

#### STDIN

> The standard input shall be used only if one or more file operands 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 paste:

> LANG
>   Provide a default value for the internationalization variables that are unset or null. (See XBD Internationalization Variables 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
>   [XSI] Determine the location of message catalogs for the processing of LC_MESSAGES.

#### ASYNCHRONOUS EVENTS

> Default.

#### STDOUT

> Concatenated lines of input files shall be separated by the <tab> (or other characters under the control of the -d option) and terminated by a <newline>.

#### 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
>   Successful completion.
> >0
>   An error occurred.

#### CONSEQUENCES OF ERRORS

> If one or more input files cannot be opened when the -s option is not specified, a diagnostic message shall be written to standard error, but no output is written to standard output. If the -s option is specified, the paste utility shall provide the default behavior described in Utility Description Defaults .

The following sections are informative.

#### APPLICATION USAGE

> When the escape sequences of the list option-argument are used in a shell script, they must be quoted; otherwise, the shell treats the <backslash> as a special character.

> Conforming applications should only use the specific <backslash>-escaped delimiters presented in this volume of POSIX.1-2008. Historical implementations treat `'\x'`, where `'x'` is not in this list, as `'x'`, but future implementations are free to expand this list to recognize other common escapes similar to those accepted by printf and other standard utilities.

> Most of the standard utilities 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

> The commands:

>     paste -d "\0" ...
>     paste -d "" ...

> are not necessarily equivalent; the latter is not specified by this volume of POSIX.1-2008 and may result in an error. The construct `'\0'` is used to mean "no separator" because historical versions of paste did not follow the syntax guidelines, and the command:

>     paste -d"" ...

> could not be handled properly by getopt().

#### EXAMPLES

> 1. Write out a directory in four columns:

>        ls | paste - - - -

> 2. Combine pairs of lines from a file into single lines:

>        paste -s -d "\t\n" file

#### RATIONALE

> None.

#### FUTURE DIRECTIONS

> None.

#### SEE ALSO

> Utility Description Defaults, cut, grep, pr

> XBD Locale, Environment Variables, Utility Syntax Guidelines

#### CHANGE HISTORY

> First released in Issue 2.

#### Issue 6

> The normative text is reworded to avoid use of the term "must" for application requirements.

#### Issue 7

> SD5-XCU-ERN-97 is applied, updating the SYNOPSIS.

> POSIX.1-2008, Technical Corrigendum 2, XCU/TC2-2008/0149 [973] is applied.

End of informative text.

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