System Configuration and Management — Use shell scripting to automate system maintenance tasks

December 30, 2010 Ed Goad

This objective is quite a bit more ethereal than the others – with no clear end game, this could mean almost anything. With that in mind, here are a few of the very basic scripts that I have found to assist in automating management. A good place to find help is the man bash page

Doing something to each file in a directory

for i in [`ls`]; do echo $i; done

Doing something for each line in a file

while read i; do echo $i; done < anaconda-ks.cfg

Repeating a task every 10 seconds

while true; do echo Hello World; sleep 10; done

Create a task that occurs the same time every day

crontab -e
Enter 1 22 * * * echo Hello World

Create a task that occurs once at a specific time/day

at 10pm Dec 31 [return]
echo Hello World [return]
[CTRL]+z

Creating an executable script

Identify a working set of bash commands and save them to a file
Add a #!/bin/bash as the first line (not required, but good form)
Execute chmod +x foo.sh to make it executable

http://www.linuxconfig.org/Bash_scripting_Tutorial is a great basic overview of bash scripting. Note that all these commands may work differently in a different shell.