Introduction to Linux in HPC/Shell scripting
Introduction to Linux in HPC/Shell scripting /
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Revision as of 12:13, 1 December 2020 by Sebastian-potthoff-3c73@uni-muenster.de (talk | contribs) (Add opening text)
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 |
In this video the concept of shell scripting is introduced. Commands entered into the console can also be written into a text file to create an executable script. The tutorial will describe how to create such a script, explain its basic structure and how to execute it in the console.
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. Find a way to execute a script without setting execute permissions.
Answer: | |
bash script.sh
|
Explanation: bash will be used as an interpreter to execute script.sh and the commands contained in script.sh will be executed sequentially.
|
3. Find out how to do other programming things in bash
(e.g. functions, classes). How convenient do they look?
Answer: |
To define a function function hello {
echo "hello, world"
}
To use this function in
hello
|
4. Look at different ways you can define if
conditions.
Answer: |
Both single square brackets str="a b"
The
if [[ $str = "a b" ]]; then
echo "it works"
fi
However, the
if [ $str = "a b" ]; then
echo "it works"
fi
To have the correct syntax for if [ "$str" = "a b" ]; then
echo "it works"
fi
|
5. Find out what 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 |
6. 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 |