proper way to detect shell exit code when errexit option set

Question

I prefer to write solid shell code, so the errexit & nounset is alway set.

The following code will stop at bad_command line

#!/bin/b         


        

Answer 1

Keep with errexit. It can help find bugs that otherwise might have unpredictable (and hard to detect) results.

#!/bin/bash
set -o errexit ; set -o nounset

bad_command || do_err_handle
good_command

The above will work fine. errexit only requires that the line pass, as you do with the bad_command && rc=0. Therefore, the above with the 'or' will only run do_err_handle if bad_command fails and, as long as do_err_handle doesn't also 'fail', then the script will continue.

Answer 2

set -o errexit

bad_command || {
  resp_code=$?
  echo Bad Thing $resp_code happened
}

Answer 3

Just trying to complete the following answer: https://stackoverflow.com/a/32201766/2609399 , which is a very good catch, BTW.

I've faced this limitation a time ago and applied a similar fix for it. Please consider the below code sample.

invokeBashFunction() {
  local functionExitCode="0"
  /bin/bash -c "
    set -o errexit

    ${*}
  " || functionExitCode="${?}"

  # add some additional processing logic/code

  return "${functionExitCode}"
}
export -f invokeBashFunction

And there are few example of how to use it:

invokeBashFunction bad_function param1 "param 2" param3 && echo "It passed." || echo "It failed!"

if invokeBashFunction bad_function param1 "param 2" param3
then
  echo "It passed."
fi

if ! invokeBashFunction bad_function param1 "param 2" param3
then
  echo "It failed!"
fi

Answer 4

In bash you can use the trap builtin which is quite nice. See https://unix.stackexchange.com/questions/79648/how-to-trigger-error-using-trap-command

Not sure how portable it is with other shells.. so YMMV

Answer 5

what if you want to know exit status of bad_command?

I think the simplest way is to disable errexit:

#!/bin/sh
set -o errexit

some_code_here

set +o errexit
bad_command
status=$?
set -o errexit
process $status

Answer 6

A clean reliable way to error exit

command_that_error_exits || { echo "Line $LINENO: Failed with Error" 1>&2; exit 1;}