What Interactive Jobs Do
Instead of submitting a batch script, interactive jobs give you a live shell on a compute node. This lets you try commands, load modules, and run programs in real time.
srun --pty bash cannot run GUI applications. If you need to run a GUI on a compute node, use salloc to allocate the node, then ssh -X to connect to it. Find the node name using squeue or the $SLURM_JOB_NODELIST environment variable.Starting an Interactive Job
Use the srun command with --pty bash to open an interactive session:
srun -p queue_name --pty bash
Replace queue_name with the partition you want (e.g., short-40core, gpu).
Requesting Resources
You can specify resources just like in batch jobs. Here are common examples:
Basic Interactive Session
srun -p short-40core --pty bash
Opens a shell on the short-40core partition with default resources.
Full Node with Time Limit
srun -p short-40core -N 1 -n 40 --time=01:00:00 --pty bash
Requests one node with 40 cores and a 1-hour time limit.
Specific Memory
srun -p short-40core-shared -N 1 -n 10 --mem=32GB --time=02:00:00 --pty bash
Requests 10 cores and 32GB of memory for 2 hours on a shared partition.
--mem are only required for shared partitions like short-40core-shared. On exclusive partitions, you get all available memory on the node by default.GPU Interactive Session
srun -p a100 --gres=gpu:1 --time=01:00:00 --pty bash
Requests one GPU on the a100 partition for 1 hour.
Common Interactive Session Options
| Option | Purpose | Example |
|---|---|---|
-p |
Partition/queue | -p short-40core |
-N |
Number of nodes | -N 1 |
-n |
Number of tasks/cores | -n 20 |
--mem |
Memory per node | --mem=64GB |
--time |
Time limit (HH:MM:SS) | --time=02:00:00 |
--gres |
Generic resources (GPU) | --gres=gpu:1 |
--pty bash |
Open interactive shell | Always at end of command |
Working in an Interactive Session
Once your interactive job starts, you'll have a shell prompt on the compute node. You can:
Load Modules
module load anaconda/3 conda activate my-env
Compile Code
gcc -o myprogram myprogram.c
Run Programs
./myprogram python script.py
Test MPI or OpenMP
export OMP_NUM_THREADS=20 ./my_openmp_program mpirun -np 40 ./my_mpi_program
Exit and Release
When finished, type exit to leave the interactive session and free resources:
exit
This returns you to the login node and cancels the interactive job.
General Tips
Request Only What You Need
Always request only the resources you need. Interactive jobs hold resources even when idle, so be conservative with your requests.
Set Reasonable Time Limits
Use --time to set an appropriate time limit. If you don't specify a time, the session may be limited by default queue policies.
Use Mostly for Testing
Interactive jobs are best for testing, debugging, and short runs. For long computations, use batch scripts with sbatch.
Don't Leave Sessions Idle
Exit your session when done. Leaving interactive sessions running wastes resources and prevents others from using those nodes.