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Re: Bash help requested: Capturing command errors within pipes



Steven W. Orr wrote:
On Thursday, Mar 19th 2009 at 14:11 -0000, quoth Daniel B. Thurman:

=>S P Arif Sahari Wibowo wrote:
=>> On Thu, 19 Mar 2009, Daniel B. Thurman wrote:
=>> > How could one go about capturing command errors within pipes?
=>> =>> The variable $PIPESTATUS is just for that. =>> =>I tried it, seems not to work.
=>
=>Try capturing a sed error when re1 or re2 has a bad regular
=>expression string.  I have not been able to catch the error.

Sorry, but you'll have to supply something more specific. It's possible for a program to have an error but not return a proper exit status.

But so far, my highly scientific test has revealed that all is good in pipe testing land in the Kingdom of Bash.

578 > true | false | true | true
579 > echo ${PIPESTATUS[ ]}
0 1 0 0

OK, I found out why I had a problem!

I setup an intentional sed error:
$ (re="-e '\'s/b/h/'"; echo "boo" | sed $re | echo "done"; echo ${PIPESTATUS})
done
sed: -e expression #1, char 1: unknown command: `''
0

Same thing but with @ pipe status expression
$ (re="-e '\'s/b/h/'"; echo "boo" | sed $re | echo "done"; echo ${PIPESTATUS[ ]})
done
sed: -e expression #1, char 1: unknown command: `''
0 1 0

My problem was that the last command was OK, of which
PIPESTATUS was reporting, thus I was not properly capturing
the exact status location where the error occurred!  duh!

Your example showed me the way!

Thanks!
Dan


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