Capturing Ctrl-c in ruby

The problem is that when a Ruby program ends, it does so by raising SystemExit. When a control-C comes in, it raises Interrupt. Since both SystemExit and Interrupt derive from Exception, your exception handling is stopping the exit or interrupt in its tracks. Here's the fix:

Wherever you can, change

rescue Exception => e
  # ...
end

to

rescue StandardError => e
  # ...
end

for those you can't change to StandardError, re-raise the exception:

rescue Exception => e
  # ...
  raise
end

or, at the very least, re-raise SystemExit and Interrupt

rescue SystemExit, Interrupt
  raise
rescue Exception => e
  #...
end

Any custom exceptions you have made should derive from StandardError, not Exception.

If you can wrap your whole program you can do something like the following:

 trap("SIGINT") { throw :ctrl_c }

 catch :ctrl_c do
 begin
    sleep(10)
 rescue Exception
    puts "Not printed"
 end
 end

This basically has CtrlC use catch/throw instead of exception handling, so unless the existing code already has a catch :ctrl_c in it, it should be fine.

Alternatively you can do a trap("SIGINT") { exit! }. exit! exits immediately, it does not raise an exception so the code can't accidentally catch it.

I am using ensure to great effect! This is for things you want to have happen when your stuff ends no matter why it ends.

If you can't wrap your whole application in a begin ... rescue block (e.g., Thor) you can just trap SIGINT:

trap "SIGINT" do
  puts "Exiting"
  exit 130
end

130 is a standard exit code.