Nl (Unix)

Template:Short description Template:Lowercase {{#invoke:Infobox|infobox}}Template:Template other{{#invoke:Check for unknown parameters | check | showblankpositional=1 | unknown = Template:Main other | preview = Page using Template:Infobox software with unknown parameter "_VALUE_"|ignoreblank=y | AsOf | author | background | bodystyle | caption | collapsetext | collapsible | developer | discontinued | engine | engines | genre | included with | language | language count | language footnote | latest preview date | latest preview version | latest release date | latest release version | latest_preview_date | latest_preview_version | latest_release_date | latest_release_version | licence | license | logo | logo alt | logo caption | logo upright | logo size | logo title | logo_alt | logo_caption | logo_upright | logo_size | logo_title | middleware | module | name | operating system | operating_system | other_names | platform | programming language | programming_language | released | replaced_by | replaces | repo | screenshot | screenshot alt | screenshot upright | screenshot size | screenshot title | screenshot_alt | screenshot_upright | screenshot_size | screenshot_title | service_name | size | standard | title | ver layout | website | qid }}Template:Main other nl is a Unix utility for numbering lines, either from a file or from standard input, reproducing output on standard output.

History

<syntaxhighlight lang="text" class="" style="" inline="1">nl</syntaxhighlight> is part of the X/Open Portability Guide since issue 2 of 1987. It was inherited into the first version of POSIX.1 and the Single Unix Specification.<ref>Template:Man</ref> It first appeared in System V release 2.<ref>Template:Man</ref>

The version of nl bundled in GNU coreutils was written by Scott Bartram and David MacKenzie.<ref>Template:Man</ref>

The command is available as a separate package for Microsoft Windows as part of the UnxUtils collection of native Win32 ports of common GNU Unix-like utilities.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Syntax

The command has a number of switches:

• a - number all lines
• t - number lines with printable text only
• n - no line numbering
• string - number only those lines containing the regular expression defined in the string supplied.

The default applied switch is t.

nl also supports some command line options.

Example

<syntaxhighlight lang="bash">

$ nl tf
    1  echo press cr
    2  read cr
    3  done

</syntaxhighlight> The following example numbers only the lines that begin with a capital letter A (matching on the regular expression /^A/). filename is optional. <syntaxhighlight lang="console"> $ nl -b p^A filename

      apple
   1  Apple
      BANANA
   2  Allspice
      strawberry

</syntaxhighlight> It can be useful as an alternative to Template:Mono: <syntaxhighlight lang="console"> $ cat somefile aaaa bbbb cccc dddc $ nl somefile | grep cccc

   3 cccc

</syntaxhighlight>

See also

• wc (Unix) – the word count command
• cat (Unix) – concatenate command (-n flag is equivalent to nl -a)
• List of Unix commands