how to avoid blocking side effect of a menu shell command

[Jenô Balaskó (IJ/ETH)]

Hi Tony,

thanks for the help.
I couldn't test it for all these shell yet :)

Regards
Attila

> -----Original Message-----
> From: discuss-bounces at nedit.org [mailto:discuss-bounces at nedit.org]On
> Behalf Of Tony Balinski
> Sent: Tuesday, August 31, 2004 6:37 PM
> To: General NEdit discussion list
> Subject: Re: how to avoid blocking side effect of a menu 
> shell command 
> 
> 
> Quoting "Jenô Balaskó (IJ/ETH)" <jeno.balasko at ericsson.com>:
> 
> > Hi all,
> >
> > could You help me, please.
> > I should execute a command 'xclearcase' from Shell menu.
> > I choosed dialog as output.
> > Unfortunately the control is blocked by this application until
> > it has been finished. Therefore the editing is stopped.
> >
> > -The usual umpersand-solution  xclearcase & doesn't work.
> > -To get back the control by pressing Ctrl-. is not user friendly.
> > -To open a new window for output instead of dialog is a 
> working solution
> > but
> > untitled files will opened.
> >
> > Is there any fancy solution like '&' to get back the 
> control immediately ?
> >
> > Thanks
> > Attila
> 
> Two things: firstly there was a problem in this area which was fixed
> not so long ago, so I would encourage you to pick up the 5.5 release
> candidate if you haven't already done so. (We're up to the second RC.)
> 
> Secondly, NEdit decides that it no longer needs to know about a
> subprocess when it sees that all file descriptors with which it
> communicates with the subprocess are closed. So the thing to do, in
> your command, is to redirect the standard input, output and error
> streams, eg
> 
>   ( your-command-goes-here ) < /dev/null >& /dev/null &
> 
> for csh.
> 
> If you use another shell for executing subprocesses (sh, ksh, bash or
> whatever), this will not work (upto version 5.4) - that was 
> the bug that
> was fixed - because NEdit did not close all unneeded file descriptors
> linked to the subprocess. You could make it work by explicitly closing
> all file descriptors (maybe using something like
>   command 0</dev/null 1>/dev/null 2>&1 3>&1 4>&1 5>&1 ... 9>&1
> - in sh or its variants - will do it).
> 
> Tony
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