Update job-scheduling.md

docs.it4i/cs/job-scheduling.md

@@ -25,12 +25,55 @@ $ squeue --me
                104   p01-arm interact    user   R       1:48      2 p01-arm[01-02]
 ```
 
-Show job details
+Show job details for specific job
 
 ```console
-$ scontrol show job 104
+$ scontrol -d show job JOBID
 ```
 
+Show job details for executing job from job session
+
+```console
+$ scontrol -d show job $SLURM_JOBID
+```
+
+## Slurm job environment variables
+
+Slurm provides usefull information to the job via environment variables. Environment variables are available on all nodes allocated to job when accessed via Slurm supported means (srun, compatible mpirun).
+
+See all Slurm variables
+```
+set |grep ^SLURM
+```
+
+Useful Slurm variables
+| variable name | description | example |
+| ------ | ------ | ------ |
+|SLURM_JOBID| job id of the executing job| 593 |
+|SLURM_JOB_NODELIST| nodes allocated to job | p03-amd[01-02] |
+|SLURM_JOB_NUM_NODES| number of nodes allocated to job | 2 |
+|SLURM_STEP_NODELIST| nodes allocated to job step | p03-amd01 |
+|SLURM_STEP_NUM_NODES| number of nodes allocated to job | 1 |
+|SLURM_JOB_PARTITION| name of the partition | p03-amd |
+|SLURM_SUBMIT_DIR| submit directory | /scratch/project/open-xx-yy/work |
+
+See [Slurm srun documentation][2] for details.
+
+Get job nodelist
+```
+$ echo $SLURM_JOB_NODELIST
+p03-amd[01-02]
+```
+
+Expand nodelist to list of nodes.
+```
+$ scontrol show hostnames $SLURM_JOB_NODELIST
+p03-amd01
+p03-amd02
+```
+
+## Running interactive jobs
+
 Run interactive job
 
 ```console
@@ -46,6 +89,8 @@ Run interactive job, with X11 forwarding
 !!! warning
     Do not use `srun` for initiating interactive jobs, subsequent `srun`, `mpirun` invocations would block forever.
 
+## Running batch jobs
+
 Run batch job
 
 ```console
@@ -278,3 +323,4 @@ $ scontrol -d show job $SLURM_JOBID | grep -i gres
 ```
 
 [1]: https://slurm.schedmd.com/
+[2]: https://slurm.schedmd.com/srun.html#SECTION_OUTPUT-ENVIRONMENT-VARIABLES