Given this Unix shell script:
test.sh:
#!/bin/sh
sleep 2 &
sleep 5 &
sleep 1 &
wait
time ./test.sh
real 0m5.008s
user 0m0.040s
sys 0m0.000s
How would you accomplish the same thing in Ruby on a Unix machine?
The sleep commands are just an example, just assume that they are long running external commands instead.
Straight from Process#waitall documentation:
fork { sleep 0.2; exit 2 } #=> 27432
fork { sleep 0.1; exit 1 } #=> 27433
fork { exit 0 } #=> 27434
p Process.waitall
Of course, instead of using Ruby's sleep, you can call whichever external command using Kernel#system, or backtick operator.
To answer my own question (just found out about this):
#!/usr/bin/ruby
spawn 'sleep 2'
spawn 'sleep 5'
spawn 'sleep 1'
Process.waitall
On ruby 1.8 you need to install the sfl gem and also require this:
require 'rubygems'
require 'sfl'
#!/usr/bin/env ruby
pids = []
pids << Kernel.fork { `sleep 2` }
pids << Kernel.fork { `sleep 5` }
pids << Kernel.fork { `sleep 1` }
pids.each { |pid| Process.wait(pid) }
