Interactive usage

Login nodes should be used only for compiling, moving data, and light pre- and postprocessing. Light means that these one-core-jobs should finish in minutes and require a few GiB of memory at maximum.

All the other interactive tasks are to be done in compute nodes via the batch job system.

Note, that for graphically intensive applications it is recommended to connect to Puhti with NoMachine.

Starting an interactive shell without X11 graphics

A bash shell can be started directly from the command line with srun instead via a job script file and sbatch. Note, as you may need to queue, it's convenient to ask for an email once the resources have been granted.

srun --ntasks=1 --time=00:10:00 --mem=1G --pty \
  --account=<project> --partition=small --mail-type=BEGIN \
  --mail-user=<your email address> bash

Once the resource has been granted, you can work normally in the shell. The bash prompt will show the name of the compute node:

[csc-username@r07c02 ~]$

Once the requested time has passed, the shell exits automatically.

Starting an interactive application with X11 graphics

To enable X11 graphics, add --x11=first to the command. The following will start the application myprog:

srun --ntasks=1 --time=00:10:00 --mem=1G --x11=first --pty \
  --account=<project> --partition=small --mail-type=BEGIN \
  --mail-user=<your email address> myprog

Note, that you can replace myprog with bash, which will launch a terminal on the compute node. From that terminal you can launch also graphical applications. Once the requested time has passed, the application will be automatically shutdown.