module Shellwords

This module manipulates strings according to the word parsing rules of the UNIX Bourne shell.

The shellwords() function was originally a port of, but modified to conform to POSIX / SUSv3 (IEEE Std 1003.1-2001).


- Wakou Aoyama
- Akinori MUSHA <>


- Akinori MUSHA <> (current maintainer)

Public Class Methods

Alias for: shellescape
Alias for: shelljoin
shellescape(str) click to toggle source

Escapes a string so that it can be safely used in a Bourne shell command line.

Note that a resulted string should be used unquoted and is not intended for use in double quotes nor in single quotes.

open("| grep #{Shellwords.escape(pattern)} file") { |pipe|
  # ...

String#shellescape is a shorthand for this function.

open("| grep #{pattern.shellescape} file") { |pipe|
  # ...

It is caller’s responsibility to encode the string in the right encoding for the shell environment where this string is used. Multibyte characters are treated as multibyte characters, not bytes.

# File rake/lib/shellwords.rb, line 73
def shellescape(str)
  # An empty argument will be skipped, so return empty quotes.
  return "''" if str.empty?

  str = str.dup

  # Treat multibyte characters as is.  It is caller's responsibility
  # to encode the string in the right encoding for the shell
  # environment.
  str.gsub!(/([^A-Za-z0-9_\-.,:\/@\n])/, "\\\\\\1")

  # A LF cannot be escaped with a backslash because a backslash + LF
  # combo is regarded as line continuation and simply ignored.
  str.gsub!(/\n/, "'\n'")

  return str
Also aliased as: escape
shelljoin(array) click to toggle source

Builds a command line string from an argument list array joining all elements escaped for Bourne shell and separated by a space.

open('|' + Shellwords.join(['grep', pattern, *files])) { |pipe|
  # ...

Array#shelljoin is a shorthand for this function.

open('|' + ['grep', pattern, *files].shelljoin) { |pipe|
  # ...
# File rake/lib/shellwords.rb, line 110
def shelljoin(array) { |arg| shellescape(arg) }.join(' ')
Also aliased as: join
shellsplit(line) click to toggle source

Splits a string into an array of tokens in the same way the UNIX Bourne shell does.

argv = Shellwords.split('here are "two words"')
argv #=> ["here", "are", "two words"]

String#shellsplit is a shorthand for this function.

argv = 'here are "two words"'.shellsplit
argv #=> ["here", "are", "two words"]
# File rake/lib/shellwords.rb, line 30
def shellsplit(line)
  words = []
  field = ''
  line.scan(/\G\s*(?>([^\s\\\"]+)|'([^\]*)'|"((?:[^\"\]|\.)*)"|(\.?)|(\S))(\s|\z)?/) do
    |word, sq, dq, esc, garbage, sep|
    raise ArgumentError, "Unmatched double quote: #{line.inspect}" if garbage
    field << (word || sq || (dq || esc).gsub(/\(.)/, '\1'))
    if sep
      words << field
      field = ''
Also aliased as: shellwords, split
Alias for: shellsplit
Alias for: shellsplit