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stdout instead of stderr

mikhailsmikhails
in Python scripting

Hi Matthias,

My script converts a GDS file into a proprietary format. The output file must go to stdout. However, layout.read() sometimes writes warnings to stdout (e.g. "Warning: Record length larger than 0x8000 encountered"), thus breaking the output file format. I need to redirect these warnings to stderr, but all my attempts with context_manager.redirect_stdout() failed. The only way to redirect seems to do this from the command-line (with > operator), but in this case, the output file is also redirected away from stdout, which is not what I want.
Can you think of a way to force klayout module functions to use stderr instead of stdout?

Thank you,

Mikhail

Comments

  • MatthiasMatthias

    HI Mikhail,

    the code to send warnings to stdout is in tlLog.cc, line 334++ (WarningChannel uses stdout).

    Without recompiling you can't change this behaviour.

    But beware: even if you manage to change this, Qt might still spit out warnings itself. These you can't redirect. I made this experience myself.

    But how come you can only send your output to stdout? I think you can always substitute such a pipeline front end with the Linux sh equivalent of:

    (app_that_writes_a_file >/dev/null 2>&1 && cat the_file_written_by_the_app) | ...

    Matthias

  • mikhailsmikhails

    Hi Matthias,

    Thank you for, as usual, a prompt and helpful reply!
    You are quite right, the stdout requirement is a bit weird, but it is not mine.
    I have found a cunning way of "deep" stdout redirection using ctypes and context manager which did the trick for me:

    https://www.programcreek.com/python/example/1108/ctypes.CDLL

    Cheers,

    Mikhail

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