get-the-output-of-running-a-system-program.md

Get The Output Of Running A System Program

Ruby has a variety of ways to execute a system program within a Ruby process. The backticks approach is the handy shorthand approach to reach for if you want to capture the output of the command.

For instance, let's say I want to capture the connection string credentials output by running a heroku command. When the command is wrapped in backticks, Ruby will execute it in a subprocess and the output of the command will be the return value.

result = `heroku pg:credentials:url DATABASE_URL --app my-app`

# extract connection details
connection_info = result.split("\n")[2].strip

With the result in hand, I can use Ruby to parse out the details I'm interested in.

Backticks does two other nice things. It allows for string interpolation and it puts the process status (e.g. exit code) on $?.