NAME
look - display lines beginning with a given string  
SYNOPSIS
look [-dfa ] [-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 (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.

Options:

-d
    Dictionary character set and order, i.e. only alphanumeric characters are compared.
-f
    Ignore the case of alphabetic characters.
-a
    Use the alternate dictionary /usr/share/dict/web2
-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 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.  
FILES

/usr/share/dict/words
    the dictionary
/usr/share/dict/web2
    the alternate dictionary