[SOLVED] bash command or function that doesn't change the error code

PeterPanic · 05-26-2021, 02:39 PM

Hi!

I'm trying to write a bash function or command that will not alter the error level of the previous command.

My application: I wat to create a $PS1 that outputs the error level of the last command (green=OK=0, red=error!=0) in my prompt ($PS1) within a function or script that returns the stdout colored string, I can never manage to KEEP the error level as it was....

As soon as I create a bash function or command that sets the color to grreen/red (echo/printf), they always return "0" as their error level.

Even if I try things like that as "color.sh:

Code:

#!/bin/bash
errorLevel=$?
case "$1" in
    "black")           printf '\e[30m' ;;
    "d-red")           printf '\e[31m' ;;
    "d-green")         printf '\e[32m' ;;
    "brown")           printf '\e[33m' ;;
    "d-blue")          printf '\e[34m' ;;
    "magenta")         printf '\e[35m' ;;
    "cyan")            printf '\e[36m' ;;
    "l-gray")          printf '\e[37m' ;;
    "d-gray")          printf '\e[90m' ;;
    "red")             printf '\e[91m' ;;
    "green")           printf '\e[92m' ;;
    "yellow")          printf '\e[93m' ;;
    "blue")            printf '\e[94m' ;;
    "pink")            printf '\e[95m' ;;
    "sky")             printf '\e[96m' ;;
    "white")           printf '\e[97m' ;;
    *)                 printf '\e[m'   ;;
 esac
exit $errorLevel

Afterwards, the error level will always be "0" ...

How can I write a function or command that does not change the error level ($?)?

smallpond · 05-26-2021, 04:06 PM

This is tricky. A bash script runs in a new, clean bash instance so it doesn't get the $? from the caller. A function runs in the same instance as the caller, but anything you do will set $?. This includes doing:

Code:

errorLevel=$?

Fortunately, the return value of the function can be set by the bash "return" command, so this works:

Code:

function preserve() {
  errorLevel=$?
  echo $errorLevel
  return $errorLevel
}

cat bazzle
cat: bazzle: No such file or directory
preserve
1
echo $?
1

PeterPanic · 05-27-2021, 12:27 PM

You saved my life (... and my error level :P ). Thanks a lot!