# Backticks syntax

`echo 'hi'`

​

# %x() syntax

%x( echo 'hi' )

​

# Kernel#system

# Executes the given command in a subshell.

system( "echo 'hi'" )

​

# Kernel#exec

# Replaces the current process by running the given external command.

exec( "echo 'hi'" )

​

# Open3

require "open3"

​

Open3.popen3('nroff -man') { |stdin, stdout, stderr| ... }

Just call: ruby your_program.rb

​

# or

​

start your program with #!/usr/bin/env ruby,

make your file executable by running 

    `chmod +x your_program.rb`

# and do 

  `./your_program.rb some_param`