How to detect an error at the beginning of a pipeline?











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In my script I need to work with the exit status of the non-last command of a pipeline:



 do_real_work 2>&1 | tee real_work.log


To my surprise, $? contains the exit code of the tee. Indeed, the following command:



false 2>&1 | tee /dev/null ; echo $?


outputs 0. Surprise, because the csh's (almost) equivalent



false |& tee /dev/null ; echo $status


prints 1.



How do I get the exit code of the non-last command of the most recent pipeline?










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    up vote
    0
    down vote

    favorite












    In my script I need to work with the exit status of the non-last command of a pipeline:



     do_real_work 2>&1 | tee real_work.log


    To my surprise, $? contains the exit code of the tee. Indeed, the following command:



    false 2>&1 | tee /dev/null ; echo $?


    outputs 0. Surprise, because the csh's (almost) equivalent



    false |& tee /dev/null ; echo $status


    prints 1.



    How do I get the exit code of the non-last command of the most recent pipeline?










    share|improve this question
























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      In my script I need to work with the exit status of the non-last command of a pipeline:



       do_real_work 2>&1 | tee real_work.log


      To my surprise, $? contains the exit code of the tee. Indeed, the following command:



      false 2>&1 | tee /dev/null ; echo $?


      outputs 0. Surprise, because the csh's (almost) equivalent



      false |& tee /dev/null ; echo $status


      prints 1.



      How do I get the exit code of the non-last command of the most recent pipeline?










      share|improve this question













      In my script I need to work with the exit status of the non-last command of a pipeline:



       do_real_work 2>&1 | tee real_work.log


      To my surprise, $? contains the exit code of the tee. Indeed, the following command:



      false 2>&1 | tee /dev/null ; echo $?


      outputs 0. Surprise, because the csh's (almost) equivalent



      false |& tee /dev/null ; echo $status


      prints 1.



      How do I get the exit code of the non-last command of the most recent pipeline?







      sh pipeline






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked Nov 15 at 0:14









      Mikhail T.

      9831129




      9831129
























          1 Answer
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          accepted










          Bash has set -o pipefail which uses the first non-zero exit code (if any) as the exit code of a pipeline.



          POSIX shell doesn't have such a feature AFAIK. You could work around that with a different approach:



          tail -F -n0 real_work.log &
          do_real_work > real_work.log 2>&1
          kill $!


          That is, start following the as yet non-existing file before running the command, and kill the process after running the command.






          share|improve this answer





















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            1 Answer
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            active

            oldest

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            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes








            up vote
            1
            down vote



            accepted










            Bash has set -o pipefail which uses the first non-zero exit code (if any) as the exit code of a pipeline.



            POSIX shell doesn't have such a feature AFAIK. You could work around that with a different approach:



            tail -F -n0 real_work.log &
            do_real_work > real_work.log 2>&1
            kill $!


            That is, start following the as yet non-existing file before running the command, and kill the process after running the command.






            share|improve this answer

























              up vote
              1
              down vote



              accepted










              Bash has set -o pipefail which uses the first non-zero exit code (if any) as the exit code of a pipeline.



              POSIX shell doesn't have such a feature AFAIK. You could work around that with a different approach:



              tail -F -n0 real_work.log &
              do_real_work > real_work.log 2>&1
              kill $!


              That is, start following the as yet non-existing file before running the command, and kill the process after running the command.






              share|improve this answer























                up vote
                1
                down vote



                accepted







                up vote
                1
                down vote



                accepted






                Bash has set -o pipefail which uses the first non-zero exit code (if any) as the exit code of a pipeline.



                POSIX shell doesn't have such a feature AFAIK. You could work around that with a different approach:



                tail -F -n0 real_work.log &
                do_real_work > real_work.log 2>&1
                kill $!


                That is, start following the as yet non-existing file before running the command, and kill the process after running the command.






                share|improve this answer












                Bash has set -o pipefail which uses the first non-zero exit code (if any) as the exit code of a pipeline.



                POSIX shell doesn't have such a feature AFAIK. You could work around that with a different approach:



                tail -F -n0 real_work.log &
                do_real_work > real_work.log 2>&1
                kill $!


                That is, start following the as yet non-existing file before running the command, and kill the process after running the command.







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Nov 15 at 0:35









                l0b0

                33.1k1583144




                33.1k1583144






























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