ri Kernel\#trap

------------------------------------------------------------ Kernel#trap
     Signal.trap( signal, proc ) => obj
     Signal.trap( signal ) {| | block } => obj
------------------------------------------------------------------------
     Specifies the handling of signals. The first parameter is a signal
     name (a string such as ``SIGALRM'', ``SIGUSR1'', and so on) or a
     signal number. The characters ``SIG'' may be omitted from the
     signal name. The command or block specifies code to be run when the
     signal is raised. If the command is the string ``IGNORE'' or
     ``SIG_IGN'', the signal will be ignored. If the command is
     ``DEFAULT'' or ``SIG_DFL'', the operating system's default handler
     will be invoked. If the command is ``EXIT'', the script will be
     terminated by the signal. Otherwise, the given command or block
     will be run. The special signal name ``EXIT'' or signal number zero
     will be invoked just prior to program termination. trap returns the
     previous handler for the given signal.

         Signal.trap(0, proc { puts "Terminating: #{$$}" })
         Signal.trap("CLD")  { puts "Child died" }
         fork && Process.wait

     produces:

         Terminating: 27461
         Child died
         Terminating: 27460