What would be the best way to check the exit status in an if statement in order to echo a specific output?
I'm thinking of it being:
if [ $? -eq 1 ] then echo "blah blah blah" fi The issue I am also having is that the exit statement is before the if statement simply because it has to have that exit code. Also, I know I'm doing something wrong since the exit would obviously exit the program.
9 Answers
Every command that runs has an exit status.
That check is looking at the exit status of the command that finished most recently before that line runs.
If you want your script to exit when that test returns true (the previous command failed) then you put exit 1 (or whatever) inside that if block after the echo.
That being said, if you are running the command and are wanting to test its output, using the following is often more straightforward.
if some_command; then echo command returned true else echo command returned some error fi Or to turn that around use ! for negation
if ! some_command; then echo command returned some error else echo command returned true fi Note though that neither of those cares what the error code is. If you know you only care about a specific error code then you need to check $? manually.
Note that exit codes != 0 are used to report errors. So, it's better to do:
retVal=$? if [ $retVal -ne 0 ]; then echo "Error" fi exit $retVal instead of
# will fail for error codes == 1 retVal=$? if [ $retVal -eq 1 ]; then echo "Error" fi exit $retVal An alternative to an explicit if statement
Minimally:
test $? -eq 0 || echo "something bad happened"
Complete:
EXITCODE=$? test $EXITCODE -eq 0 && echo "something good happened" || echo "something bad happened"; exit $EXITCODE $? is a parameter like any other. You can save its value to use before ultimately calling exit.
exit_status=$? if [ $exit_status -eq 1 ]; then echo "blah blah blah" fi exit $exit_status For the record, if the script is run with set -e (or #!/bin/bash -e) and you therefore cannot check $? directly (since the script would terminate on any return code other than zero), but want to handle a specific code, @gboffis comment is great:
/some/command || error_code=$? if [ "${error_code}" -eq 2 ]; then ... Just to add to the helpful and detailed answer:
If you have to check the exit code explicitly, it is better to use the arithmetic operator, (( ... )), this way:
run_some_command (($? != 0)) && { printf '%s\n' "Command exited with non-zero"; exit 1; } Or, use a case statement:
run_some_command; ec=$? # grab the exit code into a variable so that it can # be reused later, without the fear of being overwritten case $ec in 0) ;; 1) printf '%s\n' "Command exited with non-zero"; exit 1;; *) do_something_else;; esac Related answer about error handling in Bash:
3If you are writing a function – which is always preferred – you can propagate the error like this:
function() { if <command>; then echo worked else return fi } Now, the caller can do things like function && next as expected! This is useful if you have a lot of things to do in the if block, etc. (otherwise there are one-liners for this). It can easily be tested using the false command.
Using Z shell (zsh) you can simply use:
if [[ $(false)? -eq 1 ]]; then echo "yes" ;fi When using Bash and set -e is on, you can use:
false || exit_code=$? if [[ ${exit_code} -ne 0 ]]; then echo ${exit_code}; fi This might only be useful in a limited set of use-cases, I use this specifically when I need to capture the output from a command and write it to a log file if the exit code reports that something went wrong.
RESULT=$(my_command_that_might_fail) if (exit $?) then echo "everything went fine." else echo "ERROR: $RESULT" >> my_logfile.txt fi 
