look

Display lines beginning with a given string. As look performs a binary search, the lines in file must be sorted.

Syntax
      look [-df] [-t termchar] string [file ...]

Options:

     -d      Dictionary character set and order,
             i.e., only alphanumeric characters 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 are compared.

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.

ENVIRONMENT
The LANG, LC_ALL and LC_CTYPE environment variables affect the execution of the look utility. Their effect is described in environ(7).

FILES
 /usr/share/dict/words the dictionary

EXIT STATUS
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.

BUGS
Lines are not compared according to the current locale's collating order. Input files must be sorted with LC_COLLATE set to `C'.

“Enjoy the little things, for one day you may look back and realize they were the big things” ~ Robert Brault

Related:

look man page - Apple.com
grep - Search file(s) for lines that match a given pattern
sort - Sort text files