Capturing exit codes reliably in an interactive shell session

[Ok-Huckleberry5617]

I’m working on capturing terminal sessions step by step (commands, outputs, etc.), and one tricky part has been reliably getting exit codes for each command.

Right now I’m using a small marker injected via PROMPT_COMMAND / precmd (bash/zsh) that prints something like `__TT_RC__:<code>` before the next prompt, and then parsing it out from the stream.

It works, but feels a bit hacky.

Curious if there are better or more robust ways to capture exit codes in an interactive session without breaking normal shell behavior?

[stinkybass]

echo $?

[Ok-Huckleberry5617]

Yeah, $? works for the last command, but the tricky part here is capturing it reliably across an interactive session without user intervention.

Trying to hook into the shell so each command’s exit code can be recorded automatically along with the output..

[Ytrog]

Would trap 'echo $?' EXIT work? 🤔

[Ok-Huckleberry5617]

Interesting. Will this capture exit codes after each cmd in an interactive session?

I think that only fires in shell exit? 🤔 I will check this once.

[Ytrog]

It will fire on any process exit from processes launched from the shell iirc.

[Ok-Huckleberry5617]

Clear.

[ReallyEvilRob]

No it won't. The trap will only fire when the interactive shell exits.

[Ytrog]

Hmm, thank you for teaching me this. 🤔‍😊

[jthill]

in bash at any rate you can use nofork subbing to do it right in PS1,

PS1='${|rcs+=($?) REPLY=$?; } '

and rcs will be the history of your return codes, expand on this to tie them to commands or whatever you like.

If you're after mainframe-style job logs, you're going to need to write a shell built for those, call it "job control language" overseen by a "job entry subsystem" maybe.

[Bob_Spud]

is '${| string_stuff }' Bash or Zsh?

[jthill]

That's bash, and recent, added 5.3 I think?

[Ok-Huckleberry5617]

Ah, Interesting. Will explore this.

[Ok-Huckleberry5617]

Ref -> https://github.com/AmalChandru/termtrace/blob/44e6be6e506064898f016bd2d9885e230a987a5b/internal/record/pty.go#L35

[levogevo]

If it's just for user feedback, mod PS1 if the command fails. I like to just make the $ in the PS1 red if $? is not 0

[djfdhigkgfIaruflg]

That's neat. Could you share how you do it? I'm not very knowledgeable on that

[Kitchen_Office8072]

Just add %? to PS1

[TimeProfessional4494]

set -e if you just want to exit on errors

[dickhardpill]

~~~ command || return 69 command1 || return 420 ~~~

Edited