Suppressing the output of a command run using 'system' method while running it in a ruby script

Question

I am not sure if this makes sense but I am thinking if there is a way to suppress the output shown for a command when run using the system method in ruby? I mea

Answer 1

As an addendum, I've been surprised a few times when I've used backticks and saw output "slipping past" my variables when running scripts from the command line.

Invariably, the issue is that the text I'm seeing is actually coming from stderr rather than stdout. So, to wrangle that text into stdout as well, remember to append 2>&1 to the command you're trying to run.

I hope that's helpful to someone. I just wasted twenty minutes re-learning this lesson :)

Answer 2

• define null_device, it's operating systems dependent: windows 7 and newer use nul, while *nix systems uses /dev/null
• run the command
• redirect it's standard and error output to null_device
• then use the exit code, or the backtick method as mentioned by @mikej to determine the output

as follows:

 null_device = Gem.win_platform? ? "/nul" : "/dev/null"

 do method
   system "run command 1>#{null_device} 2>#{null_device} "
   p ($? == 0)
 end