Re: Unfortunate error message for invalid executable

[Chet Ramey]

On 5/28/22 4:56 PM, AA via Bug reports for the GNU Bourne Again SHell wrote:
> I'm sure I'm not the first person to want to have a long philosophical 
> conversation with the engineer that put the bolt I need to to reach in 
> order to fix my car, in the place that requires me to disassemble 20 other 
> unrelated things. Nor am I likely to be the first person to want to reclaim 
> the time wasted by such choices.

I know it's bait, but I'll bite. I'm sure it would be a short conversation,
along the lines of risk analysis showing the likelihood of that bolt
failing was small enough that its placement was deemed a low priority, and
that higher priority parts (in terms of both failure rate and assembly
constraints) were made more accessible.


> While I understand all of these arguments, they seem to me to be 
> inappropriately brushing off the issue based on highly technical and 
> simultaneously highly user unfriendly reasoning. Bash, in the end, is a 
> user space tool that is directly aimed at interfacing humans to the 
> machine. It is, after all a *shell*.

You'll be pleased to hear that bash-5.2 behaves the way you want, the
result of

https://lists.gnu.org/archive/html/bug-bash/2021-10/msg00020.html

back early last October.


> Therefore, IMHO it is very hard to argue with the fact that the file passed 
> to the kernel does in fact exist and therefore that ENOENT is provably 
> false *for the path with which the user is directly interacting*. It seems 
> therefore valid that, irrespective of kernel/distribution/etc/etc if ENOENT 
> is returned when executing a path that does in fact exist, bash could print 
> something more than the error string expansion of ENOENT (whether being 
> obtuse about it is an anachronistic unix-ism or not).

ENOENT really can happen. Consider a hashed command whose target is
removed after hashing, without checkhash enabled. Uncommon, you say? Maybe.
But so is this scenario. So you have to check it; you can't just assume
that ENOENT means the required interpreter was not found.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/