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cclark
Asked: 2012-10-03 21:42:47 +0800 CST

Is it possible in a script to tell if it is being run from within GNU screen?

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We have a long running process on a remote server which is kicked off manually from time to time. Unfortunately internet connections die, kernels panic and a whole host of other challenges can be encountered by the ssh session used to connect and start the job.

Screen seems like a perfect way to ensure the process isn't interrupted. However, relying on a person to always remember to start screen and then run the script to start the process is a problem waiting to happen. Is there a way from the script I can check to see if the script is being called from within screen? If it is the process will continue otherwise the script will exit with a message instructing the user to run screen first.

gnu-screen

2 Answers

  1. Best Answer

    There is an environment variable for that. If it is being run within screen, $TERM will be screen. It's that simple; just do an if on it. For instance,

    if [ $TERM != 'screen' ]; then echo foo; else echo bar; fi

    will echo bar when in screen; foo otherwise.

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  2. While you're working with screen, why not run the script with 'nohup'? This will also ensure that it continues to run if you get disconnected.

    It outputs to a file by default, so you can use other tools to monitor script output if you wish.

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