Mixlib::ShellOut

Provides a simplified interface to shelling out while still collecting both standard out and standard error and providing full control over environment, working directory, uid, gid, etc.

No means for passing input to the subprocess is provided.

Example

Simple Shellout

Invoke find(1) to search for .rb files:

  require 'mixlib/shellout'
  find = Mixlib::ShellOut.new("find . -name '*.rb'")
  find.run_command

If all went well, the results are on stdout

  puts find.stdout

find(1) prints diagnostic info to STDERR:

  puts "error messages" + find.stderr

Raise an exception if it didn't exit with 0

  find.error!

Advanced Shellout

In addition to the command to run there are other options that can be set to change the shellout behavior. The complete list of options can be found here: https://github.com/chef/mixlib-shellout/blob/master/lib/mixlib/shellout.rb

Run a command as the www user with no extra ENV settings from /tmp with a 1s timeout

  cmd = Mixlib::ShellOut.new("apachectl", "start", :user => 'www', :env => nil, :cwd => '/tmp', :timeout => 1)
  cmd.run_command # etc.

STDIN Example

Invoke crontab to edit user cron:

  # :input only supports simple strings
  crontab_lines = [ "* * * * * /bin/true", "* * * * * touch /tmp/here" ]
  crontab = Mixlib::ShellOut.new("crontab -l -u #{@new_resource.user}", :input => crontab_lines.join("\n"))
  crontab.run_command

Windows Impersonation Example

Invoke "whoami.exe" to demonstrate running a command as another user:

  whoami = Mixlib::ShellOut.new("whoami.exe", :user => "username", :domain => "DOMAIN", :password => "password")
  whoami.run_command

Invoke "whoami.exe" with elevated privileges:

  whoami = Mixlib::ShellOut.new("whoami.exe", :user => "username", :domain => "DOMAIN", :password => "password", :elevated => true)
  whoami.run_command

NOTE: The user 'admin' must have the 'Log on as a batch job' permission and the user chef is running as must have the 'Replace a process level token' and 'Adjust Memory Quotas for a process' permissions.

Platform Support

Mixlib::ShellOut does a standard fork/exec on Unix, and uses the Win32 API on Windows. There is not currently support for JRuby.

See Also

• Process.spawn in Ruby 1.9+
• https://github.com/rtomayko/posix-spawn

Contributing

For information on contributing to this project see https://github.com/chef/chef/blob/master/CONTRIBUTING.md

License

• Copyright:: Copyright (c) 2011-2016 Chef Software, Inc.
• License:: Apache License, Version 2.0

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.