Nl (Unix)
Operating system | Unix and Unix-like |
---|---|
Platform | Cross-platform |
Type | Command |
License | coreutils: GPLv3+ |
nl is a Unix utility for numbering lines, either from a file or from standard input, reproducing output on standard output.
History
nl
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.[1] It first appeared in System V release 2.[2]
The version of nl
bundled in GNU coreutils was written by Scott Bartram and David MacKenzie.[3]
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.[4]
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
$ nl tf 1 echo press cr 2 read cr 3 done
The following example numbers only the lines that begin with a capital letter A (matching on the regular expression /^A/). filename is optional.
$ nl -b p^A filename apple 1 Apple BANANA 2 Allspice strawberry
It can be useful as an alternative to grep -n:
$ cat somefile aaaa bbbb cccc dddc $ nl somefile | grep cccc 3 cccc
See also
- wc (Unix) – the word count command
- cat (Unix) – concatenate command (-n flag is equivalent to nl -a)
- List of Unix commands
References
- ^
nl
– Shell and Utilities Reference, The Single UNIX Specification, Version 4 from The Open Group - ^
nl(1)
– FreeBSD General Commands Manual - ^
nl(1)
– Linux General Commands Manual - ^ "Native Win32 ports of some GNU utilities". unxutils.sourceforge.net.
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