CODEWITHSUNDEEP
bashpbs
cs_alumnus
cs_alumnus

Reputation: 1659

How can I tell if a PBS script was called by bash or qsub

I have a PBS script that processes several environment variables. PBS is a wrapper for bash that sends the bash script to a job scheduling queue. The processed variables form a command to run a scientific application. A PBS script is written in bash with additional information for the job scheduler encoded in the bash comments.

How can I determine programmatically if my script was called by qsub, the command that interprets PBS scripts, or if it as called by bash?

If the script is running under bash I would like to treat the call as a dry run and only print out the command that was generated. In that way it bypasses the job queue entirely.

Upvotes: 2

Views: 917

Answers (2)

konsolebox
konsolebox

Reputation: 75488

You can check the parent caller of bash:

CALLER=$(ps -p "$PPID" -o comm=)
if [[ <compare $CALLER with expected process name> ]]; then
    <script was called by qsub or something>
fi

Extra note: Bash always has an unexported variable set: $BASH_VERSION so if it's set you'd be sure that the script is running with Bash. The question left would just be about which one called it.

Also, don't run the check inside a subshell () as you probably would get from $PPID the process of same shell, not the caller.

If your script is called with deeper levels in which case $PPID would not be enough, you can always recursively scan the parent pids with ps -p <pid> -o ppid=.

Upvotes: 1

merlin2011
merlin2011

Reputation: 75565

This may not be completely robust, but one heuristic which may work is to test for the existence of any of the following environmental variables which tend to be defined under qsub, as listed here.

PBS_O_HOST (the name of the host upon which the qsub command is running)
PBS_SERVER (the hostname of the pbs_server which qsub submits the job to)
PBS_O_QUEUE (the name of the original queue to which the job was submitted)
PBS_O_WORKDIR (the absolute path of the current working directory of the qsub command)
PBS_ARRAYID (each member of a job array is assigned a unique identifier)
PBS_ENVIRONMENT (set to PBS_BATCH to indicate the job is a batch job, or to PBS_INTERACTIVE to indicate the job is a PBS interactive job)
PBS_JOBID (the job identifier assigned to the job by the batch system)
PBS_JOBNAME (the job name supplied by the user)
PBS_NODEFILE (the name of the file contain the list of nodes assigned to the job)
PBS_QUEUE (the name of the queue from which the job was executed from)
PBS_WALLTIME (the walltime requested by the user or default walltime allotted by the scheduler)

Upvotes: 3

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