How to call shell commands from Ruby

Question

How do I call shell commands from inside of a Ruby program? How do I then get output from these commands back into Ruby?

Answer 1

One more option:

When you:

• need stderr as well as stdout
• can't/won't use Open3/Open4 (they throw exceptions in NetBeans on my Mac, no idea why)

You can use shell redirection:

puts %x[cat bogus.txt].inspect
  => ""

puts %x[cat bogus.txt 2>&1].inspect
  => "cat: bogus.txt: No such file or directory\n"

The 2>&1 syntax works across Linux, Mac and Windows since the early days of MS-DOS.