1.\" Copyright (c) 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)look.1 8.1 (Berkeley) 6/14/93 29.\" $FreeBSD: head/usr.bin/look/look.1 289677 2015-10-21 05:37:09Z eadler $ 30.\" 31.Dd January 12, 2016 32.Dt LOOK 1 33.Os 34.Sh NAME 35.Nm look 36.Nd display lines beginning with a given string 37.Sh SYNOPSIS 38.Nm 39.Op Fl df 40.Op Fl t Ar termchar 41.Ar string 42.Op Ar 43.Sh DESCRIPTION 44The 45.Nm 46utility displays any lines in 47.Ar file 48which contain 49.Ar string 50as a prefix. 51As 52.Nm 53performs a binary search, the lines in 54.Ar file 55must be sorted. 56.Pp 57If 58.Ar file 59is not specified, the file 60.Pa /usr/share/dict/words 61is used, only alphanumeric characters are compared and the case of 62alphabetic characters is ignored. 63.Pp 64The following options are available: 65.Bl -tag -width indent 66.It Fl d , -alphanum 67Dictionary character set and order, i.e., only alphanumeric characters 68are compared. 69.It Fl f , -ignore-case 70Ignore the case of alphabetic characters. 71.It Fl t , -terminate Ar termchar 72Specify a string termination character, i.e., only the characters 73in 74.Ar string 75up to and including the first occurrence of 76.Ar termchar 77are compared. 78.El 79.Sh ENVIRONMENT 80The 81.Ev LANG , LC_ALL 82and 83.Ev LC_CTYPE 84environment variables affect the execution of the 85.Nm 86utility. 87Their effect is described in 88.Xr environ 7 . 89.Sh FILES 90.Bl -tag -width /usr/share/dict/words -compact 91.It Pa /usr/share/dict/words 92the dictionary 93.El 94.Sh EXIT STATUS 95The 96.Nm 97utility exits 0 if one or more lines were found and displayed, 981 if no lines were found, and >1 if an error occurred. 99.Sh COMPATIBILITY 100The original manual page stated that tabs and blank characters participated 101in comparisons when the 102.Fl d 103option was specified. 104This was incorrect and the current man page matches the historic 105implementation. 106.Pp 107The 108.Fl a 109and 110.Fl -alternative 111flags are ignored for compatibility. 112.Sh SEE ALSO 113.Xr grep 1 , 114.Xr sort 1 115.Sh HISTORY 116A 117.Nm 118utility appeared in 119.At v7 . 120.Sh BUGS 121Lines are not compared according to the current locale's collating 122order. 123Input files must be sorted with 124.Ev LC_COLLATE 125set to 126.Ql C . 127