look - macOS


The look command searches for a specific pattern within a given file or a list of files. It is a powerful tool for text analysis, data extraction, and file content examination.


look [options] <pattern> [file1 file2 ...]


  • -a: Follow symbolic links.
  • -b: Print byte offsets instead of line numbers.
  • -c: Count occurrences of the pattern instead of printing lines.
  • -d: Ignore text in double-quoted strings.
  • -e: Treat the pattern as an Extended Regular Expression (ERE).
  • -f: Read the pattern from a file.
  • -i: Ignore case distinctions while matching.
  • -l: Only print the line number where the pattern is found.
  • -n: Print line numbers.
  • -s: Consider input files as a single large file.
  • -v: Invert the match, printing lines that do not contain the pattern.
  • -x: Only print full-line matches.


Simple Search:

look for "error" myfile.txt

Counting Occurrences:

look -c "\[ERROR\]" log.log

Case-Insensitive Search:

look -i for "Error" myfile.txt

Extended Regular Expression:

look -e 'a{2,}' testfile.txt

Common Issues

  • Missing Files: Verify that the specified files exist and have the correct permissions.
  • Invalid Pattern: Ensure that the pattern is valid and matches the expected format.
  • No Results: Check if the input file contains the pattern or if the options are set correctly.


  • Combine with grep for filtering and complex pattern matching.
  • Use with xargs to process multiple files based on the search results.
  • Create scripts to automate file analysis and report generation.
  • grep
  • egrep
  • sed
  • awk