Re: Inner exit status code

On 2024-05-07 10:24:49, Marek Lukács <[email protected]> spake thus:
>Is it possible to capture last exit status code after screen finished (eg.
>environment variable $SCREEN_EXIT_CODE), or copy last status code to screen'
>s exit status code, so I can check it using $? ?

Hi Marek,

I'm not aware of any way to cause a program's exit status to be 
reflected in the exit status of 'screen' itself. But even if that 
were possible, it would probably be less reliable than you would 
want, because the ability to detect an error by the status code 
would then depend on the order in which subprocesses exit within 
screen.

E.g., if a given screen session runs two subprocesses, and the first 
one exits with a non-zero (error) status and the other exits with a 
zero (success) status a moment later, then having the "last exit 
status code" reflected in the exit status of the screen process 
would still mask the error of the subprocess that failed.

A different approach would be to use wrapper scripts that write 
their exit statuses to some well-known location in the file 
system. Rather than have screen launch your program(s) directly, it 
would instead launch a corresponding wrapper script:

     #!/bin/sh
     /path/to/some/program "$@"
     printf '%s\n' "$?" >> /path/to/estat

To make that approach as reliable as possible, it would be best to 
create '/path/to/estat' prior to launching the subprocess in the 
screen session. That would allow you to detect "file system full" or 
situations in which there are inadequate persmissions to write the 
exit status file.

Best regards,
-Al

-- 
a l a n   d.   s a l e w s k i
[email protected]
[email protected]
https://github.com/salewski