Display any lines in file which contain string as a prefix.
look [-df] [-t termchar] string [file]
As look performs a binary search, the lines in file must be sorted.
-d Dictionary character set and order, i.e. only alphanumeric characters are compared.
-f Ignore the case of alphabetic characters (UPPER/lower).
-t Specify a string termination character, i.e. only the characters
in string up to and including the first occurrence of termchar are compared.
If file is not specified, the dictionary file /usr/share/dict/words is used, only alphanumeric characters are compared and the case of alphabetic characters is ignored.
Exits 0 if one or more lines were found and displayed, 1 if no lines were found, and >1 if an error occurred.
The return status is the exit status of the last command executed in consequent-commands, or zero if none were executed.