Re: Help needed with systemd script

Alec Leamas <leamas.alec@xxxxxxxxx> · Sat, 14 Dec 2013 15:12:58 +0100

    On 2013-12-14 15:00, Mattia Verga
      wrote:

      Il 14/12/2013 12:55, Dridi
        Boukelmoune ha scritto:

        Hi,

On Sat, Dec 14, 2013 at 12:44 PM, Mattia Verga <mattia.verga@xxxxxxxxxx> wrote:

          Hello,
I'm trying to give a user access rights to X with xhost command.
I've created a script named '/usr/bin/boincxhost' (chmod 555) like this:

#!/bin/sh
xhost +SI:localuser:boinc &> /dev/null
exit 0

        "exit 0" will hide a non-zero exit status of the previous command.

In this case I'm not sure what's happening, but if you're running the
command in background, and don't wait for it to complete, you may be
facing a race condition.

      Ok, I tried to edit the boincxhost script in this way:

      #!/bin/sh

        xhost +SI:localuser:boinc

        sleep 1

      Now if I run the script from console I get:

      $ /usr/bin/boincxhost 

        localuser:boinc being added to access control list

        $ xhost 

        access control enabled, only authorized clients can connect

        SI:localuser:boinc

        SI:localuser:marvin

      But if I run it within systemd unit the service is started, but
      xhost command "silently" fails:

      # systemctl start boinc-client.service

        # systemctl status boinc-client.service

        boinc-client.service - Berkeley Open Infrastructure Network
        Computing Client

           Loaded: loaded (/usr/lib/systemd/system/boinc-client.service;
        disabled)

           Active: active (running) since sab 2013-12-14 14:52:25 CET;
        4s ago

          Process: 2843 ExecStopPost=/bin/rm -f /var/lib/boinc/lockfile
        (code=exited, status=0/SUCCESS)

          Process: 2947 ExecStartPre=/usr/bin/boincxhost
          (code=exited, status=0/SUCCESS)

          Process: 2944 ExecStartPre=/usr/bin/chown boinc:boinc
        /var/log/boinc.log /var/log/boincerr.log (code=exited,
        status=0/SUCCESS)

          Process: 2941 ExecStartPre=/usr/bin/touch /var/log/boinc.log
        /var/log/boincerr.log (code=exited, status=0/SUCCESS)

          Process: 2938 ExecStartPre=/bin/sleep 1 (code=exited,
        status=0/SUCCESS)

         Main PID: 2952 (boinc)

           CGroup: name=systemd:/system/boinc-client.service

                   ├─2952 /bin/bash /usr/bin/boinc --dir /var/lib/boinc

                   └─2953 /usr/bin/boinc_client --allow_multiple_clients
        --dir /var/l...

        dic 14 14:52:23 deneb systemd[1]: Starting Berkeley Open
        Infrastructure Net.....

        dic 14 14:52:24 deneb boincxhost[2947]: xhost:  unable to
          open display ""

        dic 14 14:52:25 deneb systemd[1]: Started Berkeley Open
        Infrastructure Netw...t.

        # xhost

        access control enabled, only authorized clients can connect

        SI:localuser:marvin

    I really wonder if $DISPLAY is defined within systemd's execution
    context.  IMHO, it shouldn't E. g.,  try adding

    exec &> /tmp/boincxhost.log

      set -x

      at the top of your script. That should give debug output from the
      script. I'd presume there is some error message when run from systemd.

      Or, I'm just plain wrong. Dunno :)

      --alec

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