SignalActionHandler

List current action handlers for all Signals, without having to override the current action handlers to retrieve the same information. That way, before a signal is raised, you know what the action will be.

Usage

SignalActionHandler.info
 => {
    "EXIT" => "DEFAULT",
    "HUP" => "DEFAULT",
    "INT" => "DEFAULT",
    "QUIT" => "DEFAULT",
    "ILL" => "DEFAULT",
    "TRAP" => "SYSTEM_DEFAULT",
    "ABRT" => "SYSTEM_DEFAULT",
    "IOT" => "SYSTEM_DEFAULT",
    "EMT" => "SYSTEM_DEFAULT",
    "FPE" => "SYSTEM_DEFAULT",
    "KILL" => "SYSTEM_DEFAULT",
    "BUS" => "DEFAULT",
    "SEGV" => "DEFAULT",
    "SYS" => "DEFAULT",
    "PIPE" => "DEFAULT",
    "ALRM" => "DEFAULT",
    "TERM" => "DEFAULT",
    "URG" => "SYSTEM_DEFAULT",
    "STOP" => "SYSTEM_DEFAULT",
    "TSTP" => "SYSTEM_DEFAULT",
    "CONT" => "SYSTEM_DEFAULT",
    "CHLD" => "SYSTEM_DEFAULT",
    "CLD" => "SYSTEM_DEFAULT",
    "TTIN" => "SYSTEM_DEFAULT",
    "TTOU" => "SYSTEM_DEFAULT",
    "IO" => "SYSTEM_DEFAULT",
    "XCPU" => "SYSTEM_DEFAULT",
    "XFSZ" => "SYSTEM_DEFAULT",
    "VTALRM" => "DEFAULT",
    "PROF" => "SYSTEM_DEFAULT",
    "WINCH" => "SYSTEM_DEFAULT",
    "USR1" => "DEFAULT",
    "USR2" => "DEFAULT",
    "INFO" => "SYSTEM_DEFAULT"
    }

As a best effort, the values (action handlers) are same as the standard/default ruby's Signal values. As descrb

DEFAULT: Ruby’s default handler
SYSTEM_DEFAULT: The operating system’s default handler
IGNORE: The signal will be ignored

Reference: https://ruby-doc.org/core-2.2.0/Signal.html#method-c-trap

Why not just use `Signal.trap`

Signal.trap("TERM", "IGNORE") would return the previous action handler on TERM, at the same time would set the current action handler to IGNORE.

Whereas SignalActionHandler.info["TERM"] would return the current action handler on TERM. Without you having to restore it using Signal.trap("TERM", old_handler)

Signal.trap("TERM", "IGNORE")
 => "DEFAULT"

SignalActionHandler.info["TERM"]
 => "IGNORE"

Installation

Add this line to your application's Gemfile:

gem 'signal_action_handler'

And then execute:

$ bundle

Or install it yourself as:

$ gem install signal_action_handler

Development

After checking out the repo, run

$ bundle install
$ rake install

You can also run bundle console for an interactive prompt that will allow you to experiment.

The gem has has been purely written in C, as extention for ruby.

Test

$ bundle exec rspec

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/shayonj/signal_action_handler.