List of Bash online-tutorials

Here's a list with some (by far not all of course) Bash tutorials found on the Internet.

The primary purpose of that list is to lead beginners to good tutorials and not to the wrong ones. However, the secondary purpose is to provide information to increase quality of the linked tutorials.

My expirience shows that nobody is interested when you "just send a mail to the author", even if he links a big "contact me" in his article(s). This is another try of influencing the Bash world.

Note that these recommendations are my personal opinion. Please contact me

• if you have reviews or new sites
• if you're not okay with a recommendation
• if you're the author of a mentioned site (remove link, copyright, discussion, ...)
• etc...

The recommendation-indicator "REC" used below is a number between 1 and 10 visualized as a bar:

• Not recommended to read, at best, don't click the link.
• ...
• Use it with care!
• ...
• The perfect godlike tutorial (I doubt I'll ever find it)

Name (Links to review below)	Weblink	REC indicator	Comments
Bash guide on Greg's wiki	click		This guide teaches modern stuff and good practises. I recommend to learn from it. It was written by the guys in #bash IRC channel on Freenode (mainly lhunath), because there are so many bad tutorials out there.
Steve Parker's shell scripting guide	click		Very good (not only Bash) shell scripting guide. Teaches good practices, gives background information.
Bash Guide for Beginners (review)	click		Good introduction that really requires no previous knowledge, also covers the most important unix utilities
Advanced Bash Scripting Guide (ABS) (review)	click		Though the ABS doesn't teach the really advanced and safe stuff everywhere, it's one of the most complete and best tutorials I know. You will get a very good start when you learn from it.
IBM developerWorks "Bash by example"	click(1) click(2) click(3)		Doesn't teach outdated stuff, doesn't tell you wrong things. A good start, though not that detailed.
Deadman's	click(1) click(2)		Focus isn't scripting per se. Focus is interactive use and increasing the productivity on the prompt. Teaches some nice features.
Bash Shell Programming in Linux (P. Lutus)	click		Good start. Though there are small bugs.
BASH Help at hypexr.org (review)	click		Shows you some nice stuff and links to other ressources. Not a tutorial to learn Bash, though.
Bash Programming Introduction HowTo (TLDP) (review)	click		A bit outdated, but usable as a start to get into the Bash world.
Quick guide (review)	click		Usable as a start. Doesn't teach wrong stuff, shows you good practices.
Linux Shell Scripting Tutorial v2.0 (review)	click		currently reviewing (the tutorial is also under development)
linuxconfig.org Bash Scripting Tutorial (review)	click		Teaches many outdated, unstable, undetailed stuff. You won't learn scripting from there.
LinuxCommand.org: Writing shell scripts. (review) incomplete, thus no ranking	click		Practise oriented, some mistakes/flaws, but sadly it stops in the middle

Article link: http://www.linuxconfig.org/Bash_scripting_Tutorial
Discussion link: http://www.linuxconfig.org/Talk:Bash_scripting_Tutorial UPDATE: Discussion page is gone.

Though the basic idea is nice, using flash terminal sessions and screenshots, there are many bugs or bad constructs.

Some stuff I didn't like there:

• uses external, unreliable command which instead of builtin type -p to determinate the location of a program
• lacks sane quoting
• uses function SOMENAME keyword instead of the common POSIX-compatible variant SOMENAME() to define a function
• uses backticks instead of $( ... ) for command substitution
• abuses an additional array to store positional parameters, disregarding that $@ already is array-like
• uses echo -e and the historical control character \c instead of modern The printf command
• uses for a in `seq 1 10` instead of a C-like counter loop for ((a=1; a <= 10; a++))
• the if/else stuff looks as if the test (or [ ...]) command is the only thing Bash can execute and check
• a for loop example that will explode on word-splitting
• arithmetic tests (the while/until loop examples) using the historical "old way" with test, not modern arithmetic components
• useless quoting of one-word strings (not that it hurts per se, but it shows that the author has no clue why to use quotes)
• a weird construct I don't even understand (example for stdout/err redirection): grep -r hda6 * . 1>&2 stderr.txt
• ... some other things that are less important

twkm commented some things on their http://www.linuxconfig.org/Talk:Bash_scripting_Tutorial, I liked this article there. UPDATE: Discussion page is gone.

Overall, if the author doesn't change the article, it's unusable from my point of view. At least unusable to teach sane Bash scripting.

Article link: http://www.panix.com/~elflord/unix/bash-tute.html
Discussion Link: not available

This article is usable as basic introduction into the Bash world. It doesn't teach you wrong things, and it uses correct syntax and explanations nearly everywhere. However, it's not usable as complete learning tutorial - but that is not the goal.

One point (I have to critizize something ):

• the article says that there are no C-styled for-loops in Bash, this is wrong (maybe the article is for a very old (pre 2.05b) Bash version)

Article link: http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO.html
Discussion link: not available; EMail: mikkey (AT) dynamo.com.ar

A few points:

• uses function SOMENAME instead of more common and most portable SOMENAME() to define functions
• wrong description of the if clause (says "the base [...] is if [expression];", which is wrong)
• a for-loop example will explode due to word splitting (for i in $( ls ) - evil!)
• the mentioned C-like for-loop is not the real C-like for-loop, it just calls seq(1)

I like the style this article is written in. If some points are fixed, it could be a really usable starting point for newbies.

Article link: http://www.hypexr.org/bash_tutorial.php
Discussion link: not available; EMail: scott (AT) hypexr.org

The article is usable to step into the shell world. It's not a tutorial per se, it will tell you some nice CLI-specific things like readline or completion.

Only one point:

• confusing description of the dotfiles

Article link: http://tldp.org/LDP/abs/html/
Discussion link: not available; EMail: thegrendel (AT) theriver.com

The only big problem I see with the ABS is, that the name doesn't match the reality. It doesn't teach advanced techniques. That doesn't mean the guide isn't good! It's one of the biggest, most complete and interesting Bash guides I've seen.

I don't want to write every point here that disturbs me. In general it's not that important since the mistakes or wrong assumptions it makes are minimal. Also I noticed that mistakes in example scripts vanish over the time, the author polishes his work. Thanks Mr. Cooper.

The ABS is definitely worth to read to step deeper into the Bash and commandline world of Linux (since many Linux-specific examples are there, they're unusable for Unices).

Article link: http://tldp.org/LDP/Bash-Beginners-Guide/html/
Discussion link: not available

Good introduction to bash and shell scripting, the guide is fairly complete and requires almost no previous knowledge other than be able to type some commands in a shell.

Some advices are a bit strange or outdated "Real Programmers - Most programmers will prefer to use the test built-in command" "Wherever possible, Bash users should try to use the syntax with angular brackets:($[ ])" but all in all a nice tutorial to get a good overview of shell programming starting from 0.

Article link: http://bash.cyberciti.biz/guide/Main_Page
Discussion link: use the individual MediaWiki discussion pages

Additional problem: The author rates his shell skills as "9 of 10" in his CV. After reading this tutorial personally I'd rate him 3/10

This guide got some big problems. It seems to cover a lot of material but has some pretty nasty issues, too. Examples:

• When showing how to echo variables, it shows echo $var and echo ${var} mostly without quoting.
• Lots of 'test' and not much '['. Not really a "problem" - more a style thing. But...
• test and [ and great, but what happened to \[\[? And test == is not used to check two strings are equal. You want =.
• How to deal with case insensitive matching mentions converting to lowercase with tr and doing a pattern like [tT][aA][rR]. I propose a third solution: shopt -o nomasematch
• The for loop examples reads like a how-not-to. for i in <don't do this>: < $(ls /tmp/*)>, <1 2 3 4 5>, <$files>, <$*>. Don't parse ls. Use {1..5}. Use an array for a list of files. Use quotes (and $@).
• The infinite-while-loop example has him reimplementing the bash select builtin. Not bad for an exercise, but it ought to acknowledge that bash does it better.
• the description for compound commands is wrong: It shows 3 compound commands (grouping with and without subshell) where two of the examples are the same and the reason given for using ( ) applies equally to { }
• the function definition focusses on the "function" keyword, which is the worse way
• The initial example page for pipes seems like a good list of examples of parsing things-you-do-NOT-want-to-parse
• the page explaining the special parameters misses $@, which is a very important one
• the page(s) about shell variables and environment doesn't even mention "environment" so far got better.
• backticks are not a quoting mechanism, they are a substitution mechanism. but that doesn't matter since he doesn't mention all quoting mechanisms anyways got better, but the quoting page still is misleading
• another hint that he doesn't know what he's talking about: It's said that command substitution is allowed inside backquotes (where backquotes are a quoting mechanism!) - backquotes are command substitution!
• etc. etc. etc. (nearly endless list, sadly)

Conclusion

Beside all the bashing (sorry!) above: I think the problem is the following, the author did alot using the shell, and he knows much things. Admitted. But he doesn't know and/or understand the underlying concepts of most of the stuff. This - in my personal opinion - disqualifies him as the author of a guide/tutorial for shell scripting.

But

The tutorial is under development. It improves here and there. But the code style and robustness problems still remain.

Article link: http://linuxcommand.org/writing_shell_scripts.php
Discussion link: not available

Bad:

• Difference between startup files .bash_profile and .bashrc is wrong ("Though placing your aliases and shell functions in your .bash_profile will work, it is not considered good form.")
• Reserved words (for the parser) are not disallowed as shell variable names (if the name follows the other naming rules)
• It suggests the which command, which might be popular here and there, but should not be used for various reasons
• It says, variables with UPPERCASE names are constants, this might be a good style, but it's not a programming feature. Real "constants" are made up from read-only variables
• Common mistake it shares with many other tutorials: The ANSI C escapes are not recognized by (normal) quoting mechanisms, it's the echo command that interprets them! On the other hand, it misses the quoting style that makes the shell interpreting ANSI C escape sequences.
• It suggests the function keyword to define a function, which is correct, but bad style and unportable
• It could use getopts for positional parameters, at least as an "advanced example"
• It uses the special parameters that represent the positional parameters ($@) unquoted, and thus unsafe or buggy
• Slightly wrong: Not only SIGKILL can't be trapped, also the process stop signal. But that shouldn't really matter for daily shell coding
• "Creating safe temporary files", which is about creating an unique name, should mention tools like mktemp or thelike
• It's far from complete, it "suddenly stops". Maybe it's still under development

Good:

• Practise oriented
• It explains the behaviour of unquoted variable arguments to the test command in a nice and understandable way
• It does not use expr or let for arithmetics, good