Overview

Teaching: 10 min
Exercises: 0 min

Questions

• How do we run IDL programs on the command line?

Objectives

• Launch the IDL command line interface on a login node.

• Launch the IDL command line interface on a compute node.

Loading software modules

As there can be multiple versions of software installed on SCW a system of loadable modules let you choose which version to have. IDL versions 8.4 and 8.7 are both installed. Version 8.4 is a copy licensed to Aberystwyth and can only be run by certain Aberystwyth users. 8.7 is licensed to SCW and anybody can use it.

Listing available modules

module avail

or

module av

This will produce a long list of available software modules.

IDL is found in the /apps/local/modules/languages section near the bottom of this list.

----------------------------------------------------------------------------------- /apps/local/modules/languages ------------------------------------------------------------------------------------
anaconda/2019.03       IDL/8.7                java/13                matlab/R2019b          perl/5.30.0            python/3.7.2-gnu-4.8.5
IDL/8.4                java/11                matlab/R2019a          octave/5.1.0           python/2.7.16-gnu-8.1  python/3.7.2-gnu-8.1

Loading the module

We can load the default version (8.7) of IDL by running:

module load IDL

Or we can explicitly specify a version by doing:

module load IDL/8.7

Seeing which modules are loaded

The module list command shows which modules are loaded:

$ module list
Currently Loaded Modulefiles:
  1) null      2) IDL/8.7

Unloading modules

A single module can be unloaded with the module unload command or all modules can be unloaded with the module purge command.

$ module unload IDL
$ module list
Currently Loaded Modulefiles:
  1) null

Running IDL

The standard command line version of IDL can be launched with the idl command (after loading the module).

$ module load IDL
$ idl
IDL 8.7.2 (linux x86_64 m64).
(c) 2019, Harris Geospatial Solutions, Inc.

Licensed for use by: University of Swansea
License: MNT-5515312
IDL> 

This has only launched on the login node and this should only be used for very quick and simple testing.

Now lets allocate a node using the salloc command.

$ salloc -n1 -t 0:10:0 --partition=development
salloc: Granted job allocation 188375
salloc: Waiting for resource configuration
salloc: Nodes scs0121 are ready for job
$ ssh scs0121
Last login: Fri Mar 29 11:18:51 2019 from sl1
[a.abc1@scs0121 ~]$ module load IDL
[a.abc1@scs0121 ~]$ idl
IDL 8.7.2 (linux x86_64 m64).
(c) 2019, Harris Geospatial Solutions, Inc.

Licensed for use by: University of Swansea
License: MNT-5515312
IDL> 
.
.
Do some work here
.
.
IDL> exit

[a.abc1@scs0121 ~]$ exit
logout
Connection to scs0121 closed.
$ exit
exit
salloc: Relinquishing job allocation 188375
$ 

Key Points

• IDL must be loaded through a module

• We should run computationally intensive things on a compute node, not a login node.

• Where possible we should wrap things into batch jobs that can run without user intervention.