How to recover sudo if /etc/sudoers file is invalid?

If /etc/sudoers file is damaged/changed so that sudo command cannot be invoked, the best method of saving the world is to call utility 'pkexec':

   pkexec command_to_run

For example, to edit the /etc/sudoers file is simply

   pkexec visudo

Some useful PBS/Maui commands

    Command  Description
    showq  Show a detailed list of submitted jobs
    showbf  Show the free resources (time and processors available) at the moment
    checkjob job.ID  Show a detailed description of the job job.ID
    showstart job.ID  Give an estimate of the expected started time of the job job.ID
    pbsnodes    List nodes and their state
    qdel $(qselect -u abc123) Delete all jobs belonging to user abc123