SC2319

This $? refers to a condition, not a command. Assign to a variable to avoid it being overwritten.

Problematic code:

mycommand
if [ $? -ne 0 ] && [ $? -ne 14 ]
then
  echo "Command failed"
fi

or

mycommand
[ $? -gt 0 ] && exit $?

Correct code:

mycommand
ret=$?
if [ $ret -ne 0 ] && [ $ret -ne 14 ]
then
  echo "Command failed"
fi

or

mycommand || exit $?

Rationale:

ShellCheck found a $? that always refers to a condition like [ .. ], [[ .. ]], or test.

This most commonly happens when trying to inspect $? before doing something with it, such as inspecting it again or exiting with it, without realizing that any such inspection will also overwrite $?.

In the first problematic example, [ $? -ne 14 ] will never be true because it only runs after [ $? -ne 0 ] has modified $? to be 0. The solution is to assign $? from mycommand to a variable so that the variable can be inspected repeatedly.

In the second problematic example, exit $? will always exit 0, because it only runs if [ $? -gt 0 ] returns success and sets $? to 0. The solution could again be to assign $? to a variable first, or (as shown) use mycommand || exit $? as there is no condition to overwrite $?.

Exceptions:

If you intentionally refer to a condition to get its exit status, as in [ -e file ]; exists=$?, you can ignore this warning. Alternatively, write it out as in if ! [ -e file ]; then exists=0; else exists=1; fi.

Related resources:

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