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CptZsolt
Asked: 2023-10-18 23:09:05 +0800 CST

How to start a sudo-privilage program with screen so that I can re-attach to it later?

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Here's the problem I face: I have a program that must run as root. I want that to run in a screen, but here's a twist: for admin reasons, I want to be able to re-attach to it.

I'm writing a dirty and fast restarter daemon, because the program keeps on failing in very misterious ways, that is running as sudo (because I need root priv. to start the app). However I don't want to simply run screen as sudo, because then screen -ls won't show it, only sudo screen -ls. If I run sudo -u USER screen -dmS SCREEN_NAME sudo APP, it seems to work fine, it's listed with normal screen -ls, however there's a problem. If I want to check on the program, and try to reattach to the screen, after trying (and typing the password), the screen is terminated.

I don't have a problem with the password, the problem is that the reattached screen is terminating. Has anyone any suggestions, how I could start the screen from bash with these conditions?

debian

1 Answers

  1. Best Answer

    screen is terminating because the program is terminating. If you want to see its output you can either log it (use -L) to examine the complete output afterwards, or, to see last few lines, start a shell with the screen and run your failing application from that shell. The screen won't exit until you exit the shell.

    With -L screen will append to a logfile if it exists. You can also suggest a different filename than the default screenlog.N (N being the screen number) with -Logfile option.

    Upd: probably the confusion was caused by running screen inside sudo session like sudo screen. In that case, screen is run as root (or other user if sudo was invoked with -u argument) and you need to run subsequent operations also as that user. For example, to reattach, sudo screen -r.

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