Defensive BASH programming

#1

Post by jdkanani » Tue, Dec 15, 2015, 8:17 AM UTC

Re: Defensive BASH programming

#2

Post by ehartsuyker » Tue, Dec 15, 2015, 9:00 AM UTC

I think the best "defensive" piece of advice you left out that everyone abuses is never pipe `find` results to `xargs.` One should always do `find ... -print0` to a read-while loop because of filenames with whitespace.

Re: Defensive BASH programming

#3

Post by Gnouc » Tue, Dec 15, 2015, 9:03 AM UTC

It's said that all the example was missing quoting variables. It made all others defensive things useless.

Re: Defensive BASH programming

#4

Post by Gnouc » Tue, Dec 15, 2015, 9:04 AM UTC

ehartsuyker wrote: post #2

I think the best "defensive" piece of advice you left out that everyone abuses is never pipe `find` results to `xargs.` One should always do `find ... -print0` to a read-while loop because of filenames with whitespace.

And you also want to prevent `while` loop in shell script. See http://unix.stackexchange.com/q/169716/38906 for more details.

Re: Defensive BASH programming

#5

Post by falsedan » Tue, Dec 15, 2015, 9:06 AM UTC

All these recommendation are excellent (except omitting the necessary obsessive quoting of all variables everywhere (just in case they contain a space).

I've been enjoying BATS [0] for my bash testing.

[1] https://github.com/sstephenson/bats

Re: Defensive BASH programming

#6

Post by elevation » Tue, Dec 15, 2015, 9:15 AM UTC

ehartsuyker wrote: post #2

I think the best "defensive" piece of advice you left out that everyone abuses is never pipe `find` results to `xargs.` One should always do `find ... -print0` to a read-while loop because of filenames with whitespace.

`xargs -0' was designed to properly handle the output of `find -print0' -- no while loop needed.

`find -print0 | xargs -0 grep some_pattern'

Re: Defensive BASH programming

#7

Post by matobago » Tue, Dec 15, 2015, 9:18 AM UTC

I'm not sure if scripting can be consider programming. Excessive scripting means lack of software architecture, no to mention the least efficient way to work with the FS

Re: Defensive BASH programming

#8

Post by voltagex_ » Tue, Dec 15, 2015, 9:18 AM UTC

Does anyone know if these ideas conflict with http://mywiki.wooledge.org/BashFAQ or http://mywiki.wooledge.org/BashGuide? These are the resources that are drummed into you on #bash on Freenode, with the strong suggestion that All Other Resources Are Bad And You Should Feel Bad

Re: Defensive BASH programming

#9

Post by voltagex_ » Tue, Dec 15, 2015, 9:20 AM UTC

falsedan wrote: post #5

All these recommendation are excellent (except omitting the necessary obsessive quoting of all variables everywhere (just in case they contain a space). I've been enjoying BATS [0] for my bash testing. [1] https://github.com/sstephenson/bats

BATS looks great, but it might not be maintained any more: https://github.com/sstephenson/bats/issues

Re: Defensive BASH programming

#10

Post by dang » Tue, Dec 15, 2015, 9:24 AM UTC

Discussed last year: https://news.ycombinator.com/item?id=7815190.