Bash scripting 101

ally_uk

Hey guys does anybody have any tips on the best way to pick up and learn Bash scripting I have tried plowing my way through numerous guides. But need a similar approach to Powershell in Lunchbreaks does such a thing exist?

How did you guys get to grips with Bash scripting I need a really noob freindly guide that walks you through different scripts and mechanics slowly

Many Thanks

i.e Bash scripting for numpties

jvrlopez

To what level are you looking at being capable at?

To be honest, the way I picked up on it was to just play around with it. It was easier for me to script a few simple tasks (read, locate, grep, then uniq, and sort) then to go through and read some book. If you have some sample or working scripts that you like, I'd recommend looking at their lines and seeing how they function.

I wrote a simple bash automation script to start up a cuckoo sandbox and bring up Firefox for a new employee who wanted it done. He had never done any bash scripting before but took my template, ran with it, and did a good job touching it up.

ArabianKnight

I got this awhile back and it was helpful. The Linux Command Line: A Complete Introduction: William E. Shotts Jr.: 9781593273897: Amazon.com: Books

DoubleNNs

I was going to recommend the above book as well. You could also get it for free on their website LinuxCommand.org: Learn the Linux command line. Write shell scripts. but I liked the formatting on the production version better.

After finishing up The Linux Command Line I'm now following up w/ Unix Shell Programming (3rd Edition): Stephen G. Kochan, Patrick Wood: 9780672324901: Amazon.com: Books
Currently 2/3rd of the way thru and altho it's pretty dry, the knowledge inside is great.

the_Grinch

I agree that you should just start writing scripts. Find a task you want to automate, plan out how it should work, and start typing. I didn't have a lot of knowledge, but I wrote a script without too much trouble. My script does the following:

Go to three websites and download a file
Perform hash on the files that are downloaded
Perform hash on the original files
Compare the hashes
If hashes match, send email saying that the file hasn't changed and place it in an archive folder
If hashes don't match, perform a diff, then email the diff file to me, and then move to failure folder

philz1982

ArabianKnight wrote: »

I got this awhile back and it was helpful. The Linux Command Line: A Complete Introduction: William E. Shotts Jr.: 9781593273897: Amazon.com: Books

I used this book reading a chapter every morning when i woke up.

JockVSJock

Totally free

Linux Shell Scripting Tutorial - A Beginner's handbook

Also check out thegeekstuff.com too

ally_uk

I want to be capable of writing scripts for basic system administration tasks. Such as backing up files, Opening a specfic firewall port or automating adding a system user that kind of thing.

I also would like to create a menu for scripts where you can run options and call other scripts is that possible? I.e create a admin menu with options such as backup, install package, open port

Currently I am comfortable with commands and concepts and use Vim as my editor of choice, Scripting wise I can write basic stuff i.e chain commands together to run in a sequence, echo out stuff and get input from whoever runs the script.

I have tried to work my way through some material like advanced bash scripting and beginners guides but found them both to be dry and sleep inducing.

hiddenknight821

I used Pro Bash Programming book written by Chris Johnson. It has some good fundamental and intermediate-to-advance examples. I'd use it as my reference.

It seems like you have a solid idea what you wanted to do with a script. If you have a solid programming fundamental, then you probably can do without those books. All you probably need is a **** sheet explaining how to do the conditional test, loop, set variable, and so forth with the proper syntax. You probably also need to know some built-in shell variables. Here are some good examples starting with the dollar/peso sign which are useful in a script:

$# $? $$ $*,$@ "$*" "$@"

Again, you'd need to refer to some sources to learn and understand the power of bash scripting and use the examples as a template. Don't try to think too big. Start in a small scale. Test your program to see if it can accomplish the first task before adding more lines to the script to avoid ambiguity.

ally_uk

Thanks for the reply I guess I am a visual learner and learn best from getting hands on / watching videos I have a subscription to Udemy Bash Scripting course and have the CBT nuggets series on Bash scripting
( Old skool videos) I may sit down take things slow and build a foundation I guess I am trying to over complicate things and run before I can walk

Somebody Should write a Bash scripting project book or something that would be awesome aimed at noobs it would walk you through creating a project and gradually introducing more advanced concepts with each lesson does such a thing exist? if not why not? somebody should get writing

the_Grinch

I'm not a programmer by trade, but I believe you'd want to write functions for each of things you want to do. Thus you have the menu options appear, ask the user to enter a number, take that number and run it into a loop. That in turn will select the function that will take the settings you specify and run the task you want. I'm sure someone here might know of a better way that would make the script more efficient, but with a couple of hours of time you should be able to write that pretty quickly.

UnixGuy

I strongly recommend this book:
http://www.amazon.com/Linux-Shell-Scripting-Bash-Burtch/dp/0672326426?tag=viglink20307-20

and then this one for practice:
http://www.amazon.com/bash-Cookbook-Solutions-Examples-Cookbooks/dp/0596526784

I believe those two books are all you'll ever need...

ally_uk

Thank you for all the help guys

Unix Guy that book you recommended has been really good I am slowly working my way through it typing in various commands and examples trying to build a grounding.

Other stuff I am using

Advanced Bash Scripting Guide
Linux Shell Scripting With Bash - Ken O Burch
CBT Nuggets Video Bash scripting - Dean Davis ( really good if you are a visual learner like me )

http://bash.cyberciti.biz/guide/Menu_driven_scripts - really great site! very informative!

Built myself a basic script which has a menu and has a few functions and a Loop to run the logic

So I am gradually getting somewhere

DoubleNNs

I've heard that it's a bad idea to learn bash scripting from the Advanced Bash Scripting Guide.

ally_uk

Howcome?

nice343

check linuxcbt. The guy who teaches it is a little boring but he has an example of almost every script a network engineer/administrator will need on a daily basis.

Expect

I have also used the previously recommended Pro Bash Programming book written by Chris Johnson book. it was pretty decent.

varelg

ally_uk wrote: »

I want to be capable of writing scripts for basic system administration tasks. Such as backing up files, Opening a specfic firewall port or automating adding a system user that kind of thing.

I also would like to create a menu for scripts where you can run options and call other scripts is that possible? I.e create a admin menu with options such as backup, install package, open port

Currently I am comfortable with commands and concepts and use Vim as my editor of choice, Scripting wise I can write basic stuff i.e chain commands together to run in a sequence, echo out stuff and get input from whoever runs the script.

I have tried to work my way through some material like advanced bash scripting and beginners guides but found them both to be dry and sleep inducing.

Seems like a sys admin http based portal is what would suit you. Ah but you'd love to know what's behind the buttons...
Start with variable declaration and loops, then learn the built in variables, then pick up some sed and/or awk. Bash by itself is pretty powerful, but it has its limitations.

ally_uk

Didnt like the pro bash book thought it was a bit to above my level and a bit all over the place.

bash has limitations what would they be?

UnixGuy

Author of the Pro bash book is really opinionated..I'd stay away to be honest.

Bash has limitations but others will disagree with this statement. I wouldn't concern myself with the limitations. For system administration I think it's enough. (Keeping in mind that the world is changing now and Configuration management tools like Puppet are the new way of doing things).

DoubleNNs

DoubleNNs wrote: »

I was going to recommend the above book as well. You could also get it for free on their website LinuxCommand.org: Learn the Linux command line. Write shell scripts. but I liked the formatting on the production version better.

After finishing up The Linux Command Line I'm now following up w/ Unix Shell Programming (3rd Edition): Stephen G. Kochan, Patrick Wood: 9780672324901: Amazon.com: Books
Currently 2/3rd of the way thru and altho it's pretty dry, the knowledge inside is great.

This combo I posted above really, really helped me w/ my bash scripting. Try to read them, even if you only skim thru them, and in that order. By the time I got thru w/ them, most of the tasks I could do manually on the Linux/Unix CLI I could find a way to automate using bash shell scripting.

Once you know what the tools are, what is possible using them, and a few of the options and use cases, you can use man pages and google (stackexchange, the geekstuff, etc) to get thru the syntax.

And from those books I'd probably learn sed/awk a little bit more in depth, and then maybe seek out either a more in depth shell scripting book, or one that has more example scripts.