strace -z flag

marty leisner maleisner at
Mon Jun 10 05:29:19 UTC 2019

Hmmm....I added a -z flag over 15 years ago (to ignore failing syscalls).

I never saw it documented or in the help -- so I was about to redo my patch.


2002-11-06  Michal Ludvig  <mludvig at>

        From Marty Leisner <leisner at>,
        rewritten by mludvig:
        * strace.c (not_failing_only): New.
        (usage): Added -z switch description.
        (main): Added -z switch parsing to not_failing_only variable.
        * syscall.c (trace_syscall): Added not_failing_only handling.

I looked at the code and there's still something for -z there...

I just tried it and it still works.

I'm looking to extend it to you can filter out certain errno's -- i.e. in a
polling system, you can ignore EAGAIN and just look at real
output and real errors.

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