Linux look command

The look command in Linux is used to search for lines in a sorted file that match a given prefix. It is particularly useful when working with dictionaries or word lists.

The basic syntax of the look command is as follows:

look [options] <prefix> <file>

Here’s how you can use the look command:

  1. Searching for a prefix in a file:
    To search for lines that start with a specific prefix in a sorted file, you can simply run:
   look <prefix> <file>

Replace <prefix> with the desired prefix you want to search for, and <file> with the name of the file you want to search within.

For example, to search for words in the dictionary file (/usr/share/dict/words) that start with “apple,” you would run:

   look apple /usr/share/dict/words

The look command will display all lines that match the prefix “apple” in the specified file.

  1. Using options:
    The look command provides some additional options for customizing the search behavior. Here are a few common options:
  • -b or --binary: Treat the input file as a binary file.
  • -f or --heading: Display lines that match the prefix and their headings.
  • -t or --terse: Display only the lines that match the prefix without any additional information. You can combine these options as needed to achieve the desired output format. For example:
   look -t -f apple /usr/share/dict/words

This command will display only the lines that match the prefix “apple” without any additional information, but include the matching line’s heading.

Please note that the look command requires the file to be sorted in order for it to function correctly. If the file you are searching in is not sorted, the results may not be accurate.