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Basic Environment

Source repo: basic_skills | Branch: hpc-training-doc | Last synced: 2026-04-24 10:27:17.425 UTC

Basic system information​

Using Unix commands, we can learn a lot about the machine we are logged onto. Some of the commands are simple:

[username@login02 ~]$ date
Tue Jan 16 20:20:23 PST 2024
[username@login02 ~]$ hostname
login02
[username@login02 ~]$ whoami
username
note

To learn about most unix commands, try accessing the man pages.

[username@login02 ~]$ man date

NAME
       date - print or set the system date and time

SYNOPSIS
       date [OPTION]... [+FORMAT]
       date [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]]

DESCRIPTION
       Display the current time in the given FORMAT, or set the system date.
       ..... more info .....

Environment variables​

The unix command env will print out the environment settings for your login session.
The list below is an edited summary of all the information

warning

The output can be very long (over 90 lines)

[username@login02 ~]$ env
MODULEPATH=/opt/modulefiles/mpi/.intel:/opt/modulefiles/applications/.intel:/opt/modulefiles/mpi:/opt/modulefiles/compilers:/opt/modulefiles/applications:/usr/share/Modules/modulefiles:/etc/modulefiles
LOADEDMODULES=intel/2013_sp1.2.144:mvapich2_ib/2.1:gnutools/2.69
HOME=/home/username
SDSCHOME=/opt/sdsc
LOGNAME=username
SSH_CONNECTION=xxx.xxx.xx.xx 53640 198.202.113.253 22
DISPLAY=localhost:48.0

Printing environment variables​

It is often useful to print out (or use) environment variables. To print them out, use the echo command, and $ sign (which extracts the value of the shell variable):

[username@login02 ~]$ echo $SHELL
/bin/bash
[username@login02 ~]$ echo $HOME
/home/username

Home directory shortcut​

Another important environment variable is the home directory variable, the "tilde" character: ~

[username@login02 ~]$ echo ~
/home/username
[username@login02 ~]$

Creating environment variables​

You can create your own environment variables:

[username@login02 ~]$ MY_NAME="Super User"
[username@login02 ~]$ echo $MY_NAME
Super User

Users and groups​

Unix has the concept of users and groups. Groups are used to control access to resources (files, applications, etc.) and help establish a secure envionment Users can be in more than one group. To see which groups you are a member of, use the group command:

[username@login02 OPENMP]$ groups
abc123 pet heart scicom-docs grdclus webwrt scwpf ...