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Using Regular Expressions

Regular expressions can be used in many places, including:

  • Linux

    • GNU grep
    • The bash test command [[ "string" =~ regexp ]]
      • Note that the regular expression is not quoted
      • If you need to use a space in your regular expression, store the regex in a variable and use the variable as the regex argument in the command.
      • Example: X="ABC"; if [[ "$X" =~ ^[[:upper:]]{3}$ ]]; then echo "MATCH" ; else echo "NO MATCH" ; fi
    • The less command, using the / and ? keystrokes for searching forward and backward
    • The vi/vim editor, also using the / and ? keystrokes for searching forward and backward
    • The sed and awk utilities

  • Windows

    • findstr /R (see notes below)
    • Many PowerShell commands

  • Programming Languages (Cross-Platform)

    • Cross-platform Shells (Powershell, zsh, bash)
    • Python
    • JavaScript
    • Perl
    • C / C++ via PCRE/PCRE2 library\
    • ...and many others!