From: Kyle Schmitt [mailto:kyleaschmitt / gmail.com] 
# I know it should be streightforward, but I'm not finding the 
# docs anywhere...

what is kernel#system?

botp@botp-desktop:~$ qri kernel#system
------------------------------------------------ Kernel#system
     system(cmd [, arg, ...])    => true or false
-------------------------------------------------
Executes cmd in a subshell, returning true if the command was
found and ran successfully, false otherwise. An error status is
available in $?. The arguments are processed in the same way as
for Kernel::exec.

        system("echo *")
        system("echo", "*")

 
# How does one go about rescuing a failed shell command?  
# like in the instance it fails, or the command isn't found?

basically, you'll just have to ask it, like

 rescue_command_here unless system(my_shell_command)

lastly, you'll have to test it (because i just type this answers on my inbox w/o testing :)