Merge branch 'PR/libmount-utab-event' of github.com:karelzak/util-linux-work

[thirdparty/util-linux.git] / misc-utils / look.1.adoc

//po4a: entry man manual
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    @(#)look.1	8.1 (Berkeley) 6/14/93
////
= look(1)
:doctype: manpage
:man manual: User Commands
:man source: util-linux {release-version}
:page-layout: base
:command: look

== NAME

look - display lines beginning with a given string

== SYNOPSIS

*look* [options] _string_ [_file_]

== DESCRIPTION

The *look* utility displays any lines in _file_ which contain _string_ as a prefix. As *look* performs a binary search, the lines in _file_ must be sorted (where *sort*(1) was given the same options *-d* and/or *-f* that *look* is invoked with).

If _file_ is not specified, the file _/usr/share/dict/words_ is used, only alphanumeric characters are compared and the case of alphabetic characters is ignored.

== OPTIONS

*-a*, *--alternative*::
Use the alternative dictionary file.

*-d*, *--alphanum*::
Use normal dictionary character set and order, i.e., only blanks and alphanumeric characters are compared. This is on by default if no file is specified.
+
Note that blanks have been added to dictionary character set for compatibility with *sort -d* command since version 2.28.

*-f*, *--ignore-case*::
Ignore the case of alphabetic characters. This is on by default if no file is specified.

*-t*, *--terminate* _character_::
Specify a string termination character, i.e., only the characters in _string_ up to and including the first occurrence of _character_ are compared.

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The *look* utility exits 0 if one or more lines were found and displayed, 1 if no lines were found, and >1 if an error occurred.

== ENVIRONMENT

*WORDLIST*::
Path to a dictionary file. The environment variable has greater priority than the dictionary path defined in the *FILES* segment.

== FILES

_/usr/share/dict/words_::
the dictionary

_/usr/share/dict/web2_::
the alternative dictionary

== HISTORY

The *look* utility appeared in Version 7 AT&T Unix.

== EXAMPLES

....
sort -d /etc/passwd -o /tmp/look.dict
look -t: root:foobar /tmp/look.dict
....

== SEE ALSO

*grep*(1),
*sort*(1)

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