bash run multiple files exit condition - bash

Question

I have a function like so
function generic_build_a_module(){
move_to_the_right_directory
echo 'copying the common packages'; ./build/build_sdist.sh;
echo 'installing the api common package'; ./build/cache_deps.sh;
}
I want to exit the function if ./build/build_sdist.sh doesn't finishes successfully.
here is the content ./build/build_sdist.sh
... multiple operations....
echo "installing all pip dependencies from $REQUIREMENTS_FILE_PATH and placing their tar.gz into $PACKAGES_DIR"
pip install --no-use-wheel -d $PACKAGES_DIR -f $PACKAGES_DIR -r $REQUIREMENTS_FILE_PATH $PACKAGES_DIR/*
In other words, how does the main function generic_build_a_module "knows" if the ./build/build_sdist.sh finished successfully?

Answer 1

You can check the exit status of a command by surrounding it with an if. ! inverts the exit status. Use return 1 to exit your function with exit status 1.
generic_build_a_module() {
move_to_the_right_directory
echo 'copying the common packages'
if ! ./build/build_sdist.sh; then
echo "Aborted due to error while executing build."
return 1
fi
echo 'installing the api common package'
./build/cache_deps.sh;
}
If you don't want to print an error message, the same program can be written shorter using ||.
generic_build_a_module() {
move_to_the_right_directory
echo 'copying the common packages'
./build/build_sdist.sh || return 1
echo 'installing the api common package'
./build/cache_deps.sh;
}
Alternatively, you could use set -e. This will exit your script immediately when some command exits with a non-zero status.

Answer 2

You have to do the following:-
Run both the script in background and store their respective process id in two variables
Keep checking whether the scripts completed or not after an interval say for every 1 to 2 seconds.
Kill the process which is not completed after a specific time say 30 seconds
Example:
sdist=$(ps -fu $USER|grep -v "grep"|grep "build_sdist.sh"| awk '{print $2}')
OR
sdist=$(ps -fu $USER|grep [b]uild_sdist.sh| awk '{print $2}')
deps=$(ps -fu $USER|grep -v "grep"|grep "cache_deps.sh"| awk '{print $2}')
Now use a while loop to check the status every after a certain interval or just check the status directly after 30 seconds like below
sleep 30
if grep "$sdist"; then
kill -8 $sdist
fi
if grep "$deps"; then
kill -8 $deps
fi

Answer 3

You can check the exit code status of the last executed command by checking the $? variable. Exit code 0 is a typical indication that the command completed successfully.
Exit codes can be set by using exit followed by the code number within a script.
Here's a previous question regarding the use of $? with more detail, but to simply check this value try:
echo "test";echo $?
# Example
echo 'copying the common packages'; ./build/build_sdist.sh;
if [ $? -ne 0 ]; then
echo "The last command exited with a non-zero code"
fi
[ $? -ne 0 ] Checks if the last executed commands error code is not equal to 0. This is also useful to ensure that any negative error codes generated such as -1 are captured.
The caveat of the above approach is that we have only checked against the last command executed and not the ... multiple operations.... that you mentioned, so we may have missed an error generated by a command executed before pip install.
Depending on the situation you could set -e within a subsequent script, which instructs the shell to exit the script at the first instance a command exits with a non-zero status.
Another option would be to perform a similar operation as the example within ./build/build_sdist.sh to check the exit code of each command. This would give you the most control as to when and how the script finishes and allows the script to set it's own exit code.