Get an X window ID

Daniel Stone daniel at
Thu May 17 10:16:53 PDT 2007

On Thu, May 17, 2007 at 11:00:33AM -0500, Pat Kane wrote:
> Are you allowed to change Xlib and the X server?
> If so then this hack might help.
> A while ago I needed to know, from inside the X server,
> the PID of a process that created an X connection.
> I used spare pad bytes in the  xConnClientPrefix initial
> connection setup message to pass the PID from the client
> to the X server.  Note that clients might not be on the
> same machine so you also need the hostname of the client.

NetWM already allows you to use properties to encode the pid and
hostname of clients as window properties.  I believe the server can
already get the PID of a client via getpeerucred() or similar.

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