Re: Query info from an existing screen session?

[Sadrul Habib Chowdhury]

* Sadrul Habib Chowdhury had this to say on [01 Oct 2009, 15:58:36 -0400]:
> * Ryan Lynch had this to say on [01 Oct 2009, 15:45:04 -0400]:
> > I know that I can send commands to a running 'screen' session, using
> > the `screen -X <command>...` option, but it seems like this is a
> > one-way street.  This command never seems to return any output--if
> > there is any response, it's usually only visible inside the screen
> > session, itself.
> > 
> > Is if possible to query a running screen session for its parameters,
> > or at least redirect the status output, so that a detached script can
> > read, say, the current window list?
> > 
> 
> Not yet. I am currently in the process of adding this support, however.
> The basic framework to get back a response from an existing screen
> session has been implemented. Now the commands need to be updated to
> properly produce the response to send back as the query result. I am
> going to update the 'info', 'lastmsg' and 'windows' commands for this
> first. What other commands do you think a script might want to query?
> 
> Stay tuned!

Hey, remember this?

Well, I finally managed to update the commands for this. I have merged
the results in the main branch. If someone tries it out, please let me
know how it goes, and I am open to suggestions/requests etc.

Right now, the commands you can query are:

        echo
        info
        lastmsg
        select
        time
        title
        windows

The exit status will be non-zero if some command fails. So, for
example, you can detect if a particular window exists by looking at the
exit status of:

        'screen -Q select non-existent-window'

The man/info-pages have also been updated.

Bug reports/suggestions/requests/patches are welcome.

Cheers,
Sadrul