When to use each method of launching a subprocess in Ruby

1. `` The Backtick defined in Kernel 1. a) %x{} Percent X < alternate syntax for The Backtick defined in parse.y, see discussion 2. system() Kernel#system 3. fork() Kernel#fork, Process#fork 4. open() open a pipe Kernel#open 4.a. IO.popen() < behaves the same as open() open a pipe IO#popen 4.b. open("|-") fork to a pipe 4.c. IO.popen("-") < behaves the same as open("|-") fork to a pipe see discuss