Is this supposed to work this way?

Andrey Repin
Thu Apr 5 22:50:00 GMT 2012

Greetings, Eric Blake!

>> Well, then, following your wisdom, I have to clog every line of my script with
>> "... || exit" or an equivalent.

> No, you don't.  You can factor out your feature checks up front, in a
> way that still works with 'set -e', rather than having to give up 'set
> -e' through the entire script.  That said...

>> Because even an attempt to continue execution, if any error occured, would be
>> disastrous to the calling program.
>> Solution is to "set -e" and have script bail out at any problem,

> 'set -e' is a can of worms, best avoided if you don't want surprises.
> Consider:

> f() { set -e; false; echo hi; }
> f || echo bye

> It does NOT exit on the false.  Rather, it prints 'hi' and NOT 'bye',
> all while turning on set -e for the rest of your script.  And that
> behavior is mandated by POSIX.  My opinion is that you are better off
> coding without 'set -e' in the first place.

Well, this is interesting...

>> but if I try
>> autoconf approach and blindly run whatever I feel appropriate, hoping for the
>> best and preparing for worst, I won't have such option.

> Give us more details of a feature you're trying to test.  I'll even get
> you started with an example - suppose you want to know when to use cygpath:

> if (cygpath --version) >/dev/null 2>&1; then
>   my_convert() { cygpath "$1"; }
> else
>   my_convert() { echo "$1"; }
> fi

> foo "$(my_convert "$file")"

For provided STC, that would be enough. But the script I've striped it from is
reassembling Java application file. And if any step of preparation would fail,
it should not try to assemble it. The difference between Cygwin/Linux/Mac is
just the first stop in there.
I'll have to think about that some day, when I don't have a headache.
May be make OS-specific checks before blowing the horn, if I don't find more
elegant solution... (As I said already, I've hit a stall with readlink on Mac.)

> which will run cygpath on $file on cygwin, and will use $file unchanged
> on other platforms.  And there you have a feature check - you checked
> the feature of whether cygpath exists as an executable up front, then
> the rest of your script is now OS-independent by relying on your
> up-front setup based on the results of the feature check.

Andrey Repin ( 06.04.2012, <02:20>

Sorry for my terrible english...

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