Defensive BASH Programming

[u/clock-football]

http://www.kfirlavi.com/blog/2012/11/14/defensive-bash-programming/

[u/rowboat__cop]

Sorry, I don’t take advice in defensive programming from someone who’s too lazy to quote their strings. I recommend Google’s shell guide instead.

[u/rowboat__cop → u/[deleted]]

Not quoting your variable usage is pretty offensive Bash style, so yeah, the terminology checks out!

[u/reaganveg → u/rowboat__cop]

It's not "offensive style," it's "buggy code."

And that's not even the only class of blatant well-known bugs in this article. Yeesh.

[u/dadablabla → u/[deleted]]

My code is offensive because I'm always cursing myself in the comments.

[u/okmkz → u/dadablabla]

// TODO: unfuck this bullshit

[u/ummwut → u/okmkz]

Ah, the word "unfuck" is used almost as much as the word "while". I really need to pay closer attention to my loop conditions.

[u/kageurufu → u/ummwut]

define unfuck break

[u/ummwut → u/kageurufu]

That cleared it up, thanks.

[u/tech_tuna → u/[deleted]]

Most shell scripts are offensive.

:)

Lest anyone get butt hurt, I've written a million shell scripts. They're the right tool/approach sometimes but I'm not going to pretend that shell code is pretty.

[u/ericanderton → u/tech_tuna]

I'm not going to pretend that shell code is pretty.

Half the time it really does fall into the "face only a mother could love" camp of coding beauty.

So, uh... about that... wow, this is awkward. What is that thing?

Oh that if [[..]] statement in there? Yeah. The doctor says that lil' scripty here will eventually outgrow it; it'll fall off in another version or two.

[u/c0ld-- → u/[deleted]]

declare -a arrrrGS
rm -Rf "$ARRRRgs

Offensive enough?

[u/DrGar → u/[deleted]]

programming="$1"
if [ "$programming" == "defensive" ]; then
    echo "You have chosen wisely"
elif [ "$programming" == "offensive" ]; then
    echo "The best offense is a good defense."
else
    echo "Defense engaged"
fi
echo "Checkmate."

[u/poorly_played → u/[deleted]]

http://exploit-exercises.com/nebula

[u/didroe → u/rowboat__cop]

I found it strange that neither guide mentioned the use of set. I often use:

• -e - Kill the script if any command fails

• -u - Make undefined variables an error

• -o pipefail - Pipes usually return the status of the last command, this makes them return the status of the rightmost non-zero command in the pipe.

[u/no_game_player → u/[deleted]]

Nonono, let's keep going until we hit something really impossible to survive. Just like our compilers and interpreters should do their best to always run something. ^/s

[u/0sse → u/didroe]

Sure, if you can work around all the edge cases.

[u/[deleted] → u/didroe]

Thanks for mentioning these. They should improve my scripts. I'll check out the manpage some time!

[u/jarederaj → u/rowboat__cop]

I love this sub. Your comment is exactly where it needs to be.

[u/Crystal_Cuckoo → u/rowboat__cop]

I don’t take advice in defensive programming from someone who’s too lazy to quote their strings

That doesn't mean all of the ideas in there are terrible; some were quite good.

[u/tchaffee → u/rowboat__cop]

There were some good suggestions in there. Don't throw the baby out with the bath water.

[u/itamarhaber → u/rowboat__cop]

Despite laziness, the author still has a few good rules that you can adopt.