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I agree. Your interpretation is faithful to the intent of the original version. The way the original code is written, it assumes export cannot fail.

Do I ever check export's return status? No...

But still then I am back to my original point and that it is unlikely what the author intended, especially given the error message, so we better correct the author. BTW, do you ever check return...

Hmmm. POSIX says export returns 0 and doesn't mention any possible error conditions. However, some shells' export builtin can return a non-zero status. Perhaps it's better to be safe than sorry...

Hi, Scrutinizer:

Your interpretation is indeed correct, but its correctness hinges on export always returning 0. I mentioned that not to nitpick, but as a heads up for newbies.

Regards,...

I certainly wouldn't challenge your assertion of that. But I would challenge any assertion that said return codes are always meaningful:


/root # yum install jiggery-pokery
Loaded plugins:...

Every single command run on a UNIX/Linux/POSIX system will return an exit status. If that exit status is 0, the shell treats that as a boolean true. Any other exit status is treated as a boolean...

And which one is the best then ? (less parsing & less resource consumming) ?

A few alternatives:

if [[ -f /sunstudio12/bin/sunf90 ]]; then
export IMDI_COMPILER=/sunstudio12/bin/sunf90
if [ $? -ne 0 ]; then
echo "Please specify location!"
exit
fi
...

Now I agree with Dude Alister ... LoL

That's close but not quite correct. The original version's echo executes if the export command fails. This interpretation's does not.

Regards,
Alister

Sorry, but this is absolute tosh. A Conditional Expression is not the same as a "test" and they have their own syntax and rules. Admittedly there is some small overlap in the syntax for certain...

[[ xxx ]] is test [ xxx ], see man test or test in man ksh.

I call this "procedure as logic". Run the expresions and commands connected by && in order and keep going as long as commnads return...

I agree with the dude Scrutinizer :)

I think it is equivalent to this:
if [ $COMPILER = "sun" ]; then
if [[ -f /sunstudio12/bin/sunf90 ]]; then
export IMDI_COMPILER=/sunstudio12/bin/sunf90
else
echo "Please specify...

[[...]] && export... ||,

is one line form of

if [[ ... ]] ; then
export...
else
echo "Please ...
fi

the \ is used for cosmetic reasons : when a line is too long, you can break it by...