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:
-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 char-
acters 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
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.
A look utility appeared in Version 7 AT&T UNIX.
Lines are not compared according to the current locale's collating order.
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