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155 lines
3.9 KiB
Groff
155 lines
3.9 KiB
Groff
.\" Copyright (c) 1990, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)look.1 8.1 (Berkeley) 6/14/93
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.\"
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.Dd December 29, 2020
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.Dt LOOK 1
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.Os
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.Sh NAME
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.Nm look
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.Nd display lines beginning with a given string
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.Sh SYNOPSIS
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.Nm
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.Op Fl df
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.Op Fl t Ar termchar
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.Ar string
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.Op Ar
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.Sh DESCRIPTION
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The
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.Nm
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utility displays any lines in
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.Ar file
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which contain
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.Ar string
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as a prefix.
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As
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.Nm
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performs a binary search, the lines in
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.Ar file
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must be sorted.
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.Pp
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If
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.Ar file
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is not specified, the file
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.Pa /usr/share/dict/words
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is used, only alphanumeric characters are compared and the case of
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alphabetic characters is ignored.
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.Pp
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The following options are available:
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.Bl -tag -width indent
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.It Fl d , -alphanum
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Dictionary character set and order, i.e., only alphanumeric characters
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are compared.
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.It Fl f , -ignore-case
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Ignore the case of alphabetic characters.
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.It Fl t , -terminate Ar termchar
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Specify a string termination character, i.e., only the characters
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in
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.Ar string
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up to and including the first occurrence of
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.Ar termchar
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are compared.
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.El
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.Sh ENVIRONMENT
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The
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.Ev LANG , LC_ALL
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and
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.Ev LC_CTYPE
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environment variables affect the execution of the
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.Nm
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utility.
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Their effect is described in
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.Xr environ 7 .
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.Sh FILES
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.Bl -tag -width /usr/share/dict/words -compact
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.It Pa /usr/share/dict/words
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the dictionary
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.El
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.Sh EXIT STATUS
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The
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.Nm
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utility exits 0 if one or more lines were found and displayed,
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1 if no lines were found, and >1 if an error occurred.
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.Sh EXAMPLES
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Look for lines starting with
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.Ql xylene
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in the file
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.Pa /usr/share/dict/words :
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.Bd -literal -offset indent
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$ look xylen
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xylene
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xylenol
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xylenyl
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.Ed
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.Pp
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Same as above, but do not consider any characters in
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.Ar string
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beyond the first
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.Ql e .
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Note that
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.Fl f
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is implicit since we are searching the default file
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.Pa /usr/share/dict/words :
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.Bd -literal -offset indent
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$ look -t e xylen
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Xyleborus
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xylem
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xylene
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xylenol
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xylenyl
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xyletic
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.Ed
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.Sh COMPATIBILITY
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The original manual page stated that tabs and blank characters participated
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in comparisons when the
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.Fl d
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option was specified.
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This was incorrect and the current man page matches the historic
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implementation.
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.Pp
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The
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.Fl a
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and
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.Fl -alternative
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flags are ignored for compatibility.
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.Sh SEE ALSO
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.Xr grep 1 ,
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.Xr sort 1
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.Sh HISTORY
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A
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.Nm
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utility appeared in
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.At v7 .
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.Sh BUGS
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Lines are not compared according to the current locale's collating
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order.
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Input files must be sorted with
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.Ev LC_COLLATE
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set to
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.Ql C .
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