Thread: getting stderr from an app launched via execv

  1. #1
    Registered User
    Join Date
    Aug 2008

    getting stderr from an app launched via execv

    I have an application that calls another app and reads its output from stdout and also traps output to stderr too.

    It originally used popen and trapped stderr by passing "2>out.err" as the last parameter and it worked fine.
    But I also needed to be able to send a SIGINT to the program and couldn't using the popen architecture.

    So I've changed my code to use fork / execv and now the last parm "2>out.err" is being passed to the app and not treated the same was as it was with popen.

    So my question is, how can I trap prints to stderr from the app that I launched using execv?


  2. #2
    and the hat of int overfl Salem's Avatar
    Join Date
    Aug 2001
    The edge of the known universe
    In the child process, just before you exec...

    - open "out.err" for writing
    - close descriptor 2
    - Call dup with the descriptor from step 1
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

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