look(1) -- Linux man page



look - display lines beginning with a given string  


look [-dfa ] [-t termchar ] string [file ]  


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 (where sort(1) got the same options -d and/or -f that look is invoked with).

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.


Dictionary character set and order, i.e. only alphanumeric characters are compared.
Ignore the case of alphabetic characters.
Use the alternate dictionary /usr/share/dict/web2
Specify a string termination character, i.e. only the characters in string up to and including the first occurrence of termchar are compared.

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 dictionary
the alternate dictionary



grep(1), sort(1)  


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 appeared in Version 7 AT&T Unix.