Dear Stefan,

Thanks for the reply. I have tried your patch and it didn't solve my problem. Maybe I 
have not written my question clearly. The two frontends could run on the same computer 
if I use the remote method, i.e. by setting up the mserver and connect to the 
experiment by specifying "-h localhost", also the frontend programs need to be put in 
different directory. What I want to know is whether I can simply start multiple 
frontends in the same directory without setting up the mserver etc. I noticed that 
there are several *.SHM files, I'm not familiar with semaphore, but I guess they are 
the key to the problem. Please correct me if I misunderstood something.

Best Regards,
Jimmy


> > Dear All,
> > 
> > I want to run two frontend programs (one for trigger and one for slow control)
> > concurrently on the same computer, but I failed. The second frontend said: 
> > 
> > Semaphore already present
> >  There is another process using the semaphore.
> >  Or a process using the semaphore exited abnormally.
> >  In That case try to manually release the semaphore with:
> >    ipcrm sem XXX.
> > 
> > The two frontends are connected to the same experiment. Is there any way I can
> > overcome this problem?
> 
> That might be related to the RPC mutex, which gets created system wide now. I 
> modified this in midas.c rev. 4628, so there will be one mutex per process. Can you 
> try that temporary patch and tell me if it works for you?