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.

Syntax:

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

Example:

Options:

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

  Example:

  look "include" Assignment.c

  

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

  Example:

  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.

  Example:

  look -t b abu words

  

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

  Example:

  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.

  Example:

  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