Best practice for if/else when one outcome results in exit [Bash]

Question

I have a bash script with a lot of if/else constructs in the form of
if <condition>
then
<do stuff>
else
<do other stuff>
exit
fi
This could also be structured as
if ! <condition>
then
<do other stuff>
exit
fi
<do stuff>
The first one seems more structured, because it explicitly associates <do stuff> with the condition.  But the second one seems more logical because it avoids explicitly making a choice (then/else) that doesn't really need to be made.
Is one of the two more in line with "best practice" from pure bash or general programming perspectives?

Answer 1

I'm not sure if there are 'formal' best practices, but I tend to use the latter form when (and only when) it is some sort of error checking.
Essentially, this would be when <do stuff> was more of the main purpose of the script, or at least that neighborhood of the script, while <do other stuff> was mostly cleaning up before exiting.
I suppose more generally, it could relate to the size of the code blocks.  You wouldn't want a long involved <do stuff> section after which a reader would see an "else" and think 'WTF, else what?'.  So, perhaps if there is a substantial disparity in the lengths of the two conditional blocks, put the short one first.
But I'm just making this all up from my own preferences and intuition.
When nested this becomes more obvious, and/or a bigger issue.  Consider two scripts:
if [[ test1 ]]
then
if [[ test2 ]]
then
echo "All tests passed, continuing..."
else
echo "failed test 2"
exit
fi
else
echo "failed test 1"
fi
if [[ ! test1 ]]
then
echo "failed test 1"
exit
fi
if [[ ! test2 ]]
then
echo "failed test 2"
exit
fi
echo "passed all tests, continuing..."
This just gets far worse with deeper levels of nesting.  The second seems much cleaner.  In reality though I'd go even further to
[[ ! test1 ]] && echo "failed test 1" && exit
[[ ! test2 ]] && echo "failed test 2" && exit
echo "passed all tests, continuing..."
edit: added test1/test2 examples.
Last edited by Trilby (2012-06-19 02:27:48)