LOOK(1)                            BSD General Commands Manual                            LOOK(1)

NAME
     look — display lines beginning with a given string

SYNOPSIS
     look [-bdf] [-t termchar] string [file ...]

DESCRIPTION
     The look utility displays any lines in file which contain string as a prefix.

     If file is not specified, the file /usr/share/dict/words is used, only alphanumeric charac‐
     ters are compared and the case of alphabetic characters is ignored.

     The following options are available:

     -b      Use a binary search on the given word list. If you are ignoring case with -f or
             ignoring non-alphanumeric characters with -d, the file must be sorted in the same
             way. Please note that these options are the default if no filename is given. See
             sort(1) for more information on sorting files.

     -d      Dictionary character set and order, i.e., only alphanumeric characters are compared.

     -f      Ignore the case of alphabetic characters.

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

ENVIRONMENT
     The LANG, LC_ALL and LC_CTYPE environment variables affect the execution of the look util‐
     ity.  Their effect is described in environ(7).

FILES
     /usr/share/dict/words  the dictionary

EXIT STATUS
     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.

COMPATIBILITY
     The original manual page stated that tabs and blank characters participated in comparisons
     when the -d option was specified.  This was incorrect and the current man page matches the
     historic implementation.

     look uses a linear search by default instead of a binary search, which is what most other
     implementations use by default.

SEE ALSO
     grep(1), sort(1)

HISTORY
     A look utility appeared in Version 7 AT&T UNIX.

BUGS
     Lines are not compared according to the current locale's collating order.  Input files must
     be sorted with LC_COLLATE set to ‘C’.

BSD                                       July 17, 2004                                       BSD