LOOK(1)                     General Commands Manual                    LOOK(1)

NAME
     look – display lines beginning with a given string

SYNOPSIS
     look [-df] [-t termchar] 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.

     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:

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

     -f, --ignore-case
             Ignore the case of alphabetic characters.

     -t, --terminate termchar
             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 utility.  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.

EXAMPLES
     Look for lines starting with ‘xylene’ in the file /usr/share/dict/words:

           $ look xylen
           xylene
           xylenol
           xylenyl

     Same as above, but do not consider any characters in string beyond the
     first ‘e’.  Note that -f is implicit since we are searching the default
     file /usr/share/dict/words:

           $ look -t e xylen
           Xyleborus
           xylem
           xylene
           xylenol
           xylenyl
           xyletic

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.

     The -a and --alternative flags are ignored for compatibility.

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’.

macOS 15.2                     December 29, 2020                    macOS 15.2