look command in Linux with Examples

The look command in Linux shows the lines beginning with a given string. This command also uses binary search if the file is sorted. If file is not specified, the file /usr/share/dict/words is used. And then only the alphanumeric characters are compared and the case of alphabetic characters is ignored.


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



  • -[string]: This option is used to search for the given string in a specified file.


    look "include" Assignment.c

  • -f : This option is used to ignore case of alphabetic character.


    look -f ab words

  • -t: This option is used to specify a string termination character, i.e., only the characters in string up to and including the first occurrence of character are compared.


    look -t b abu words

  • -d: This option is used to compare only alphanumeric characters.


    look -d ab words
  • -bd, -bf: This option uses binary search on the given word list. If you are ignoring case with -f or ignoring non-alphanumeric characters with -d, the file must be sorted in the same way.


    look -bf ab words
  • -h: This option is used to show the help message and exit.
    look -h
  • -V: This option is used to show the version information and exit.
    look -V
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