Introduction to Linux in HPC/Environment variables
Introduction to Linux in HPC/Environment variables /
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Tutorial | |
---|---|
Title: | Introduction to Linux in HPC |
Provider: | HPC.NRW
|
Contact: | tutorials@hpc.nrw |
Type: | Multi-part video |
Topic Area: | HPC Platforms |
License: | CC-BY-SA |
Syllabus
| |
1. Background and History | |
2. The Command Line | |
3. Linux Directory Structure | |
4. Files | |
5. Text display and search | |
6. Users and permissions | |
7. Processes | |
8. The vim text editor | |
9. Shell scripting | |
10. Environment variables | |
11. System configuration | |
12. SSH Connections | |
13. SSH: Graphics and File Transfer | |
14. Various tips |
Video
Quiz
Which bash command below assigns "value" to variable var?
Exercises in Terminal
1. a. Write a script that b. Prints an environment variable c. Saves the output of the date command to a variable d. Sleeps briefly e. Prints the new and old date and time
Answer: |
One possible way to write the script is #!/bin/bash
echo "I am $USER, my home directory is $HOME"
olddate=$(date)
sleep 10s
echo "old date: ${olddate}"
echo "new date: $(date)"
Explanation: |
2. What do different types of quotes (single'
vs. double"
) do?
Answer: |
single quote
var=abc
echo '$var'
This script prints the literal string var=abc
echo "$var"
This script prints the value of |
3. create an shell variable MYIDENTITY and export it as below:
$ export MYIDENTITY=whoami
How will you list the shell variable MYIDENTITY?
Execute the shell variable MYIDENTITY, what is the output?
Answer: |
you can list the variable by using the echo command as follows $ echo $MYIDENTITY
whoami
The arguments passed to echo are printed to the standard output. $ $MYIDENTITY
username
The shell variable upon execution runs the command |