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

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


     -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.

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


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 shared dictionary used by look, on macOS this is censored, a number of expletives have been removed when compared to the Linux versions.
~/Library/Spelling/LocalDictionary The per-user dictionary for GUI applications.

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.

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

Related macOS commands

grep - Search file(s) for lines that match a given pattern.
sort - Sort text files.

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