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Shell Scripting

Shell Scripting​

Shell scripts execute a series of commands in one run, making repetitive tasks easy to automate. On the Omega, you typically use the Bourne shell (sh).

Sample Script​

The following script logs who ran it and when. The comments explain each step:

# Anything after the hash symbol is considered a comment.
# This script will create log of the time the script that was executed
# and the name of the person who executed it. The log will be stored in
# a file called log.txt, found in the "/" directory. The script will 
# also display the contents of the log.txt file on the terminal. 
#The line below tells Linux which shell to use for execution

#!/bin/bash 

# Create NAME variable with value name
NAME=name 

# Create DATE variable with value date
DATE=date 

#Prompt User to input their name
echo -n "Please Enter Your Name >"

#Store the value entered by the user into the variable username
read username

#Store the value of our username in NAME variable
NAME=$username

#The DATE stores the value returned by the date command. in form $(command)
DATE=$(date)

#Append the NAME and DATE values to the log.txt file
echo $NAME $DATE >> /log.txt 

#Display the contents of the log.txt file
cat /log.txt

Save the script as LogGen.sh, make it executable, and run it:

sh LogGen.sh

Run it multiple times with different names and you will see new log entries appended to /log.txt.

Shell script output

Next, learn about Ownership and Permissions to control who can run or edit the files you create.