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

If you really need Bash, per the note in the "best" answer.

First, note that when Ruby calls out to a shell, it typically calls /bin/sh, not Bash. Some Bash syntax is not supported by /bin/sh on all systems.

If you need to use Bash, insert bash -c "your Bash-only command" inside of your desired calling method:

quick_output = system("ls -la")

quick_bash = system("bash -c 'ls -la'")

To test:

system("echo $SHELL")
system('bash -c "echo $SHELL"')

Or if you are running an existing script file like

script_output = system("./my_script.sh")

Ruby should honor the shebang, but you could always use

system("bash ./my_script.sh")

to make sure, though there may be a slight overhead from /bin/sh running /bin/bash, you probably won't notice.