Bash – Capture exit code of exit command

bashexecexitexit-statusshell-script

I have this in a bash script:

exit 3;

exit_code="$?"

if [[ "$exit_code" != "0" ]]; then
    echo -e "${r2g_magenta}Your r2g process is exiting with code $exit_code.${r2g_no_color}";
    exit "$exit_code";
fi

It looks like it will exit right after the exit command, which makes sense.
I was wondering is there some simple command that can provide an exit code without exiting right away?

I was going to guess:

exec exit 3

but it gives an error message: exec: exit: not found.
What can I do? 🙂

Best Answer

If you have a script that runs some program and looks at the program's exit status (with $?), and you want to test that script by doing something that causes $? to be set to some known value (e.g., 3), just do

(exit 3)

The parentheses create a sub-shell. Then the exit command causes that sub-shell to exit with the specified exit status.

Related Solutions

Shell – Keep exit codes when trapping SIGINT and similar

All you need to do is change the EXIT handler inside your cleanup handler. Here's an example:

#!/bin/bash
cleanup() {
    echo trapped exit
    trap 'exit 0' EXIT
}
trap cleanup EXIT
read -p 'If you ctrl-c me now my return code will be the default for SIGTERM. '

Bash Exec – Practical Use Cases and Examples

exec is often used in shell scripts which mainly act as wrappers for starting other binaries. For example:

#!/bin/sh

if stuff;
    EXTRA_OPTIONS="-x -y -z"
else
    EXTRA_OPTIONS="-a foo"
fi

exec /usr/local/bin/the.real.binary $EXTRA_OPTIONS "$@"

so that after the wrapper is finished running, the "real" binary takes over and there is no longer any trace of the wrapper script that temporarily occupied the same slot in the process table. The "real" binary is a direct child of whatever launched it instead of a grandchild.

You mention also I/O redirection in your question. That is quite a different use case of exec and has nothing to do with replacing the shell with another process. When exec has no arguments, like so:

exec 3>>/tmp/logfile

then I/O redirections on the command line take effect in the current shell process, but the current shell process keeps running and moves on to the next command in the script.

Best Answer

Related Solutions

Shell – Keep exit codes when trapping SIGINT and similar

Bash Exec – Practical Use Cases and Examples

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