mvn in bash script if statement

Question

I want to run the command mvn clean in a bash script. But I want to put it in an if statement. If the clean does not run properly I would like to exit out of the bash script wit

Answer 1

Here's what you want:

mvn clean
if [ "$?" -ne 0 ]; then
    echo "Maven Clean Unsuccessful!"
    exit 1
fi

Explanation:

• $? is a special shell variable that contains the exit code (whether it terminated successfully, or not) of the most immediate recently executed command.
• -ne is an option to the test builtin [. It stands for "not equal". So here we are testing if the exit code from mvn clean is not equal to zero.
• echo "Maven Clean Unsucccessful!" - If this is the case, then we output some indicative message, and exit the script itself with an errant exit code.

When you do $(mvn clean), that instead spawns a new subshell to run mvn clean, then simply dumps everything that was output to stdout in that subshell from running mvn clean to where $(...) was used in the parent shell.

---

Alternatively, you can do:

mvn clean || { echo "Maven Clean Unsuccessful"; exit 1; }

Which is just shorthand syntactic sugar for doing the same thing.

Answer 2

I prefer to use a variable to capture the return code. Improves readability and allows running additional commands without fear of clobbering return code value:

mvn clean

MVN_RTN=$?
if [ "${MVN_RTN}" -ne 0 ]; then
   echo "Maven returned failure code ${MVN_RTN}"
   exit 1
fi

Answer 3

No parentheses needed for checking the exit status:

if mvn clean ; then
   echo ok
else
   echo Something went wrong.
   exit 1
fi