Command line playground for regular expressions
Bump version to 1.1.1
Use pflag module for option parsing
Bump version to 1.1.0



You can also use your local clone with git send-email.


Rex is a command line playground for regular expressions similar to playground section on ihateregex.io.



go get -u git.sr.ht/~yerinalexey/rex

Make sure to add $GOPATH/bin to your $PATH variable if not already:

export PATH="$PATH:$GOPATH/bin"


$ rex [flags] [file]

Rex reads file where each line is a test match (multi-line regexes are not supported). If not specified, the text is read from standard input. Lines should be separated by line feeds (\n).

In the interface you are presented with a regex input field and a list of test data highlighted accordingly to them matching a regex.

You can switch between them using Tab or Shift+Tab. Escape exits the application and prints input regex to standard output unless --print-regex=0 flag is specified.

List can be scrolled using Vi keys: j - down, k - up. Input field supports readline-like bindings: reference.

Flags/options reference:

  • --input REGEX (-i REGEX) - set default value for regex field (. if not set)
  • --print-regex (-p) - print regex after exit (true by default)
  • --version (-V) - print version number
  • --help (-h) - show help message

To turn off boolean flags, you can assign them to a value of zero after an equal sign: -p=0 or --print-regex=false.

The following values can be accepted by boolean flags: 1, 0, t, f, true, false, TRUE, FALSE, True, False.


Send patches using git send-email to my public inbox with project prefix set to rex:

git config format.subjectPrefix 'PATCH rex'