LOOK(1) BSD General Commands Manual LOOK(1)
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 charac-
ters is ignored.
The following options are available:
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.
Dictionary character set and order, i.e., only alphanumeric char-
acters are compared.
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
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 partici-
pated in comparisons when the -d option was specified. This was incor-
rect 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.
The -a and --alternative flags are ignored for compatibility.
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'.
BSD July 17, 2004 BSD