[xmonad] Strange spawnPipe error

Ferenc Wagner wferi at niif.hu
Sat Dec 26 05:59:25 EST 2009

Brent Yorgey <byorgey at seas.upenn.edu> writes:

> when xmonad starts up it fails to start dzen via spawnPipe.
> Instead, I get this error:
>   createSession: permission denied (Operation not permitted)
> Due to various debugging activites on my part it is clear that this is
> being generated by the call to spawnPipe.

spawnPipe calls createSession, which is the setsid system call.  From
man setsid:

  The only error which can happen is EPERM.  It is returned when the
  process group ID of any process equals the PID of the calling process.
  Thus, in particular, setsid() fails if the calling process is already
  a process group leader.

Since spawnPipe calls this right after forking, I don't understand how
this could happen.  Maybe strace -f could provide some insight.

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