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     look - display lines beginning with a given string


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


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

     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.

     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.


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


     /usr/share/dict/words  the dictionary


     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.


     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.


     grep(1), sort(1)


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


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