dummy DISPLAY value? - Xwindows

This is a discussion on dummy DISPLAY value? - Xwindows ; Hi, I have a problem with a software that will be executed remotely. For some reason the software wants to connect to an Xserver, we dont really need that, but the software will not run if it can connect. e.g. ...

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  1. dummy DISPLAY value?

    Hi,

    I have a problem with a software that will be executed remotely.
    For some reason the software wants to connect to an Xserver,
    we dont really need that, but the software will not run if it can
    connect.

    e.g. if I do a login on a work station, I can execute the software
    fine

    but if I do a telnet to the very same work station from another
    computer I cannot execute the software.

    Question: How can I call the software so that it "thinks" that
    everything is fine and that a display is available?

    I have tried
    export DISPLAY ":42000.0"
    and other things, but it doesnt work....

    Note: the software does not deliver any output to the display, it
    basically just demands to have one available......

    I desperatly need help on this one!

  2. Re: dummy DISPLAY value?

    In comp.windows.x, Mike Smith

    wrote
    on 10 Feb 2004 02:54:13 -0800
    :
    > Hi,
    >
    > I have a problem with a software that will be executed remotely.
    > For some reason the software wants to connect to an Xserver,
    > we dont really need that, but the software will not run if it can
    > connect.
    >
    > e.g. if I do a login on a work station, I can execute the software
    > fine
    >
    > but if I do a telnet to the very same work station from another
    > computer I cannot execute the software.
    >
    > Question: How can I call the software so that it "thinks" that
    > everything is fine and that a display is available?
    >
    > I have tried
    > export DISPLAY ":42000.0"
    > and other things, but it doesnt work....
    >
    > Note: the software does not deliver any output to the display, it
    > basically just demands to have one available......
    >
    > I desperatly need help on this one!


    You might look into Xvfb; it's an X server that can run on machines
    with no display hardware and no physical input devices. It can
    also create screendumps.

    --
    #191, ewill3@earthlink.net
    It's still legal to go .sigless.

  3. Re: dummy DISPLAY value?

    On Tue, 10 Feb 2004, Mike Smith wrote:

    > Hi,
    >
    > I have a problem with a software that will be executed remotely.
    > For some reason the software wants to connect to an Xserver,
    > we dont really need that, but the software will not run if it can
    > connect.
    >
    > e.g. if I do a login on a work station, I can execute the software
    > fine
    >
    > but if I do a telnet to the very same work station from another
    > computer I cannot execute the software.
    >
    > Question: How can I call the software so that it "thinks" that
    > everything is fine and that a display is available?
    >
    > I have tried
    > export DISPLAY ":42000.0"
    > and other things, but it doesnt work....
    >
    > Note: the software does not deliver any output to the display, it
    > basically just demands to have one available......
    >
    > I desperatly need help on this one!


    We use some software like that (NASA SeaDAS, written in IDL), running on
    SGI Irix. The easiest fix would be to use xfb, but AFAIK that isn't
    available on Irix. Another trick is to put linux on an old notebook and
    just leave XF86 running there.

    For our situation, a cover script that searches for a working
    Xserver before starting the program does the trick. SeaDAS often used to
    make images after a calculation that runs for days, so you can't assume
    that an Xserver that was running when the jobs started will still be going
    when you need it.

    function get_Xserver
    {
    for h in $(generate_list_of_potential_servers) ; do
    if xdpyinfo -display ${h}:0 > /dev/null ; then
    export DISPLAY=${h}:0
    break
    fi
    done
    print $DISPLAY
    }

    # find a working X-server
    if xdpyinfo -display ${DISPLAY:-unknown} > /dev/null ; then
    print -u2 "$pgm: using Xserver <$DISPLAY>"
    else
    DISPLAY=unknown

    DISPLAY=$(get_Xserver)
    if [ "$DISPLAY" = "unknown" ] ; then
    print -u2 "$pgm: no available X-server"
    exit 1
    else
    print -u2 "$pgm: using Xserver <$DISPLAY>"
    fi
    fi

    --
    George N. White III
    Head of St. Margarets Bay, Nova Scotia, Canada

  4. Re: dummy DISPLAY value?

    Thanks, Xvfb did the trick, unfortunately that means that Xwindows has
    to be installed :/
    but at least it is a solution.

    M

  5. Re: dummy DISPLAY value?

    In comp.windows.x, Mike Smith

    wrote
    on 23 Feb 2004 23:14:31 -0800
    :
    > Thanks, Xvfb did the trick, unfortunately that means that Xwindows has
    > to be installed :/
    > but at least it is a solution.
    >
    > M


    There are other solutions available, of varying effectiveness.
    It depends on your needs:

    [1] ssh -X . /etc/ssh/sshd_config needs X11Forwarding
    set to "yes" (this may be a minor security issue;
    I don't know, but it's far more secure than xhost,
    over the Internet), and then one will have the ability
    to display things on the local X server from a remote
    machine.

    [2] The usual (and insecure) options: xhost +remote on the local box.

    [3] Xnest. This interesting solution basically opens an X server
    within an X window within another X server.

    [4] Xvfb, your current solution that defines an Xserver with
    no input.

    Gotta like X's flexibility. :-)

    --
    #191, ewill3@earthlink.net
    It's still legal to go .sigless.

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