From: Luis Gracia (
Date: Fri Jul 30 2004 - 14:26:52 CDT

I checked your suggestion, but unfortunatly, '&' doesn't seem to work
when opening a pipe, even thought the manual says that the command
follows the same style as 'exec'. Anyway, I went back to save a file and
then input it to xmgrace. Thanks, Luis

John Stone said the following on 07/29/04 22:50:
> Did you try adding an ampersand to the end of the piped command
> i.e.:
> set pipe_id [open "| xmgrace -pipe & " w]
> When used with Tcl's own exec that allows you to run in the background,
> so if you're lucky it'll work for your piped command as well. If not
> there's probably still a good way of doing it similarly.
> John Stone
> On Thu, Jul 29, 2004 at 08:09:04PM -0400, Luis Gracia wrote:
>>Hi everyone,
>>this is more of a tcl question. I am trying to run an external program
>>(xmgrace) from a vmd plugin, and would like to execute it and without
>>closing xmgrace use vmd normally. I was able to open xmgrace from within
>>the plugin, but vmd freezes until I close xmgrace. Is there any way to
>>tell tcl not to wait till xmgrace is finished?
>>This is code that makes troubles:
>> set pipe_id [open "| xmgrace -pipe" w]
>> fconfigure $pipe_id -buffering line
>> puts $pipe_id "@page size 576, 432"
>> .....
>> close $pipe_id

Luis Gracia, PhD
Department of Physiology & Biophysics
Weill Medical College of Cornell University
1300 York Avenue, Box 75
New York, NY 10021
Tel: (212) 746-6375
Fax: (212) 746-6361