Hi,
Comming on this very old thread:
On Wed, 4 Dec 2013 14:40:11 -0500, Greg Wooledge wrote:
>
> The most obvious difference is that $? is shorter.
>
> $? is also POSIX standard (older than POSIX in fact), so it works in sh
> scripts as well. PIPESTATUS is a Bash extension.
>
> Finally, note that if you execute a pipeline, $? will contain the exit
> status of the last command in the pipeline, not the first command,
> which is what ${PIPESTATUS[0]} would contain. (If you execute a simple
> command instead of a pipeline, then they would both have the same value.)
Some asked on StackOverflow.com:
Why does a Bash while loop result in PIPESTATUS "1" instead of "0"?
https://stackoverflow.com/q/78351657/1765658
Then after some tests:
if ls /wrong/path | wc | cat - /wrong/path | sed 'w/wrong/path' >/dev/null ;
then
echo Don't print this'
fi ; echo ${?@Q} ${PIPESTATUS[@]@A} $(( $? ${PIPESTATUS[@]/#/+} ))
ls: cannot access '/wrong/path': No such file or directory
cat: /wrong/path: No such file or directory
sed: couldn't open file /wrong/path: No such file or directory
'0' declare -a PIPESTATUS=([0]="2" [1]="0" [2]="1" [3]="4") 7
Where $PIPESTATUS[0]=>2 and $?=>0 !!
I could explain that '$?' is result of bash's if...then...fi group command
executed correctly and PIPESTATUS hold result of "most-recently-executed
foreground pipeline", but man page say:
PIPESTATUS
An array variable (see Arrays below) containing a list of exit
status values from the processes in the most-recently-executed
foreground pipeline (which may contain only a single command).
? Expands to the exit status of the most recently executed fore‐
ground pipeline.
If so, "$?" have to be equivalent to "${PIPESTATUS[0]}", I think.
I suggest that man page should be modified to replace "foreground pipeline"
by "command" under "?" paragraph.
--
Félix Hauri - <fe...@f-hauri.ch> - http://www.f-hauri.ch
