Re^2: Effect of redirecting output to /dev/null on $? value

Thanks for the explanation. I ran a different, more complex application with a deliberate seg fault added again using my method above and now see the following as the output:

sh: line 1: 26902 Segmentation fault      my_complex_executable_that_s
+egfaults > /dev/null
return value is 35584
exit_value = 139
signal_num = 0
dumped_core = 0
[download]

In the above case, 0x80 | signal_num = 0x80 | 0x0B = 0x8B = 139, which matches the listed exit_value. 35584 is just the exit value shifted up 8 bits, which is consistent with the definition of $?.

What does the 26902 value indicate? Is that the 16-bit status int set by wait(2) from running my_complex_executable_that_segfaults that can be parsed by perl to assemble the fields of the $? variable, and can also be accessed directly in C/C++ using the macros WTERMSIG, WEXITSTATUS, etc. (source: https://linux.die.net/man/2/wait)?

Comment on Re^2: Effect of redirecting output to /dev/null on $? value Select or Download Code

Replies are listed 'Best First'.
Re^3: Effect of redirecting output to /dev/null on $? value by jcb (Parson) on Aug 04, 2020 at 01:17 UTC
What does the 26902 value indicate? The shell generated that message to report that a subprocess with PID 26902 exited with a segmentation fault. The hint is that it starts with "`sh: line 1:`". The shell sees your command as a one-line shell script.	[reply]
Re^3: Effect of redirecting output to /dev/null on $? value by ikegami (Patriarch) on Aug 03, 2020 at 16:50 UTC
What does the 26902 value indicate? pid? I don't think I've ever seen a message like that. It's not a exit status. 26902 = 0x6916. As a status, this would mean the process exited with code 0x69 and it was killed by signal 0x16, but those are mutually exclusive.	[reply]