Skip to content

Converting Torque Job Scripts to SLURM

This page is intended for users who already know SLURM basics and want to convert their existing Torque job scripts. It focuses only on the differences you need to care about, and on using the pbs2slurm tool to automate much of the work.

Why Conversion is Needed

Torque job scripts use #PBS directives, Torque-specific environment variables, and resource options like ppn. SLURM uses #SBATCH directives, different environment variables, and separates concepts like tasks and CPUs per task. Directly running Torque scripts under SLURM will not work.

Header Conversion

The biggest change is the job headers.

Header Conversion

The largest change is that Torque used #PBS headers, while SLURM uses #SBATCH.

Purpose Torque Example SLURM Equivalent (default)
Job name #PBS -N myjob #SBATCH --job-name=myjob
Nodes/CPUs #PBS -l nodes=2:ppn=16 #SBATCH --nodes=2
#SBATCH --ntasks=1
#SBATCH --cpus-per-task=16
Walltime #PBS -l walltime=02:00:00 #SBATCH --time=02:00:00
Memory #PBS -l mem=8gb #SBATCH --mem=8G
Output file #PBS -o job.out #SBATCH --output=job.out
Error file #PBS -e job.err #SBATCH --error=job.err
Billing account #PBS -A research #SBATCH --account=research

Note

  • The table above shows the default translation for threaded (OpenMP/pthreads) jobs: one process with many CPUs.
  • If your job is MPI-based, you should instead request multiple tasks per node: 
    #SBATCH --nodes=2
#SBATCH --ntasks-per-node=16
#SBATCH --cpus-per-task=1
  • pbs2slurm defaults to the threaded style, and will add a comment when ppn is defined, reminding you to check if your workload is MPI.

Environment Variable Mapping

Update these references in your scripts:

Purpose Torque Variable SLURM Variable
Submit directory $PBS_O_WORKDIR $SLURM_SUBMIT_DIR
Job ID $PBS_JOBID $SLURM_JOB_ID
Job name $PBS_JOBNAME $SLURM_JOB_NAME
Node file $PBS_NODEFILE $SLURM_NODELIST
Process count $PBS_NP $SLURM_NTASKS

Interactive Jobs

  • Torque:
qsub -I -l nodes=1:ppn=4,walltime=01:00:00
  • SLURM:
salloc -A research --nodes=1 --ntasks=4 --time=01:00:00

Tip

In SLURM, once you have an allocation with salloc, launch programs inside it with srun.

Billing Accounts

New to SLURM, we require a billing account.

  • SLURM: #SBATCH --account=research in the script, or sbatch -A research job.sh

You can set defaults so you don’t have to type -A every time:

export SBATCH_ACCOUNT=research
export SRUN_ACCOUNT=research
export SALLOC_ACCOUNT=research

Using the pbs2slurm Converter

We provide a utility, pbs2slurm, that automatically translates most Torque headers into SLURM.

Usage

pbs2slurm -h
usage: pbs2slurm [-h] [-q] [-s SHELL] [-d] [-V] infile

positional arguments:
  infile                PBS/MOAB input file to convert.

options:
  -h, --help            show this help message and exit
  -q, --quiet           Disable conversion instructions in output.
  -s SHELL, --shell SHELL
                        Shell to use for script if it doesn't already have one.
  -d, --debug           Display some debug messages
  -V                    show program's version number and exit

Example

pbs2slurm myjob.pbs > myjob.sh

This produces a new SLURM script (myjob.sh) with #SBATCH directives and updated environment variables. If pbs2slurm encounters an option it cannot convert, it will insert a comment in the output for manual review.

Warning

pbs2slurm is a helper, not a guarantee. Always read the converted script before running it. Complex Torque directives (GPU requests, node properties, job arrays) may require manual adjustment.

Common Gotchas When Converting

  • ppn: Torque used ppn (“processors per node”). Replace with --ntasks and/or --cpus-per-task.
  • Output/error handling: Torque combined stdout/stderr unless separated; SLURM keeps them separate.
  • Node list: Torque wrote explicit hostnames to $PBS_NODEFILE. SLURM gives $SLURM_NODELIST (range format).
  • tracejob: Torque’s tracejob has no SLURM equivalent. Use sacct for completed jobs.

Next Steps

  1. Run your existing Torque scripts through pbs2slurm.
  2. Review and fix any TODOs or flagged lines.
  3. Submit a small test job under SLURM.
  4. Compare results with your old Torque workflow.

For more details, see the SLURM usage guide.