How to Write a shell alias or function for quick login to a node managed by SLURM#
For tasks better run in a dedicated but interactive fashion, it might be advantageous to save the repeating pattern of reserving resources and starting a new associated shell in an alias or function, as explained below.
If you use bash as default shell you can place the following alias
definition in your ~/.bashrc file and source this file in the
~/.bash_profile or in the ~/.profile file:
alias get-node='salloc --x11 --mem=10G -p interactive -A <prj-account>'
where <prj-account> needs to be replaces by a valid project
account authorizing you to use Slurm.
If you use tcsh as default shell you can put the following line in
your ~/.cshrc or ~/tcshrc file to define the alias get-node:
alias get-node 'salloc --x11 --mem=10G -p interactive -A <prj-account>'
Thereafter, the command get-node can be used to allocate computing
resources and log into the allotted node in one step:
$ get-node
salloc: Pending job allocation 292893
salloc: job 292893 queued and waiting for resources
salloc: job 292893 has been allocated resources
salloc: Granted job allocation 292893
salloc: Waiting for resource configuration
salloc: Nodes l12345 are ready for job
userid@l12345:~>
An even more flexible solution is to define a shell function that accepts options to specify resources requirements likely to change (e.g. number of tasks, memory amount, partition, project account).
The example below defines a bash function get-node that can be
added to your ~/.bashrc file:
get-node(){
# set default values for number of tasks, partition, account, and time limit
ntasks=1
partition=interactive
account=$SALLOC_ACCOUNT
timelimit=08:00:00
OPTIND=1
# parse options with arguments
while getopts :n:p:a: opt; do
case ${opt} in
n ) ntasks=$OPTARG
;;
p ) partition=$OPTARG
;;
a ) account=$OPTARG
;;
t ) timelimit=$OPTARG
;;
\? ) echo "Invalid option: $OPTARG" 1>&2
return
;;
: ) echo "Invalid option: $OPTARG requires an argument" 1>&2
return
;;
esac
done
# allocate ressources and log into the allotted node
salloc --x11 -A ${account} -n ${ntasks} -p ${partition} -t ${timelimit}
}
and used to start interactive sessions according to different needs, for example:
# ask for 4 CPUs on one node from the interactive partition using account from SALLOC_ACCOUNT
$ get-node -n 4
# allocate ressources for 4 hours and use account xz0456 instead of the default account
$ get-node -a xz0456 -t 240
# use compute partition (for interactive debugging purposes)
$ get-node -p compute
Tcsh or csh do not allow for shell functions. This deficiency
can be partly compensated for by defining an alias with positional
parameters as shown in the example below:
alias get-node 'salloc --x11 -n \!:1 -p \!:2 -A \!:3'
However, for tcsh or csh, all parameters MUST be specified and
the order of parameters (in the example above number of tasks,
partition, account) DOES matter:
# ask for 4 CPUs on a node from the interactive partition using account xz0123
$ get-node 4 interactive xz0123
# use account xz0456 instead of default account
$ get-node 1 interactive xz0456
Another possibility (not shown here) is to write a Unix utility using
a language of your choice (python, perl etc.), place it in your
~/bin directory and add this directory to your PATH.