"Writing a shell script is like riding a bike."

[eppur_se_muova]

Writing a shell script is like riding a bike. You fall off and scrape your knees a lot at first. With a bit more experience, you become comfortable riding them around town, but also quickly discover why most people drive cars for longer trips.

https://developer.apple.com/library/content/documentation/OpenSource/Conceptual/ShellScripting/shell_scripts/shell_scripts.html#//apple_ref/doc/uid/TP40004268-CH237-SW3

[Fullduplexxx]

1. You have to pedal like hell to get up a hill?

[lapfog_1]

2. shell scripts are the APL of scripting languages.

good for a one time action, not generally maintainable or provable ( only because they are generally written without much thought as to error recovery or unexpected input handling )

Speaking as someone who has written code and scripts for a living for over 35 years now.

I rarely see well-documented shell scripts.

[Hermit-The-Prog]

3. exceptions

There are exceptions to that. I wrote one to back up files to CDs, 'way back before DVDs. It contains full documentation -- name, license, where to get it, outline (I., II., III., etc., of process, variables, user prompts, checks, functions), and finishes with "# an added attraction for those who are not easily offended by bad ascii art" -- an ASCII flowchart.

I used that thing even after DVDs came along because the target maximum "iso" image was set by user input. Of course, hard drives became a cheaper backup media very near the same time as DVDs appeared.

Then there is the 44K bash script I wrote which is a prime example of your rule. Its purpose was to tie a conglomerated mess of a business data system together. They had a dos-based data entry system whose output had to be transmogrified to go into a postgresql database on a GNU/Linux system to produce monthly bills and reports. It worked for 6 years and was chock full of 'corner cases'. There are bits and pieces of it I might be able to explain now. It became a sort of Jenga -- edit only certain parts known not to break.

[Hermit-The-Prog]

4. deep, dark secrets of bash

The Deep, Dark Secrets of Bash By Ben Okopnik
http://tldp.org/LDP/LG///////////issue55/okopnik.html

(Contains links to some more bashing by same author)

[hunter]

5. "MS-DOS is sniffing glue..."

There's a parallel universe where Bill Gates and Steve Jobs graduated from Berkeley.

It's probably a better place.