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Help Message for Shell Scripts

samizdat.dev

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Re: Help Message for Shell Scripts

#101

Post by ahnick »

gpanders wrote: post #61
ahnick wrote: post #43

Earlier quoted context omitted.

Ah interesting, is there any workaround for Mac? Otherwise, I may just have to fallback to stripping the man page formatting and sending it to less.

The actual `man` command does this: /usr/bin/tbl | /usr/bin/groff -Wall -mtty-char -Tascii -mandoc -c | /usr/bin/less -is So you could do it "manually" that way. Not the cleanest or prettiest solution but it's much lighter weight than using something like pandoc. EDIT: Full example: { /usr/bin/tbl | /usr/bin/groff -Wall -mtty-char -Tascii -mandoc -c | /usr/bin/less -is; }

Thanks, this worked well on Mac.

Re: Help Message for Shell Scripts

#103

Post by gorgoiler »

The power is out on your boat, again. It’s 3am. You suspect that, again, the alternator housing has come loose.

You duct tape a flashlight to the bulkhead so you can work hands free and actually see what you are doing. All you have on you is a broken pocket knife but it’ll do because all you need to accomplish right now is to tighten the housing screws enough. You know this for a fact because you’ve done it three times already in the last 24 hours.

It’s not even a documented procedure — you’ll replace the housing mounts entirely when you’re back at port in three days’ time. You guarantee it — this is the first thing you’ll do even, when you get back to shore. You have my word on that, captain!

The duct tape came unstuck. It was damp and doesn’t work so well (at all) when it’s wet. The flashlight survived the fall. More tape this time should do the job. Tape mount version 2 will still unstick of course, eventually. Nothing stops the damp at sea, but if you use enough tape then you’ll have fixed the power by the time the tape fails. That’s your plan B and you’re sticking to it.

Sure, you could do this job better if you had an impact driver with an automatically illuminated bit chuck, but buying one of those is further down the todo list than fixing the power on the boat, making it back to port, and ensuring the power doesn’t fail this way again, as promised. Or at least won’t fail for the next few shifts.

On your days off you relax by programming in Bash.

Re: Help Message for Shell Scripts

#104

Post by dungdongdang »

amelius wrote: post #36
psophis wrote: post #8

Earlier quoted context omitted.

You can also use add a hyphen ( https://linuxhint.com/bash-heredoc-tutorial/

Seriously, bash has too many obscure features.

a commonly used feature that has been a part of the unix standard since before "bash" only meant to hit something with a heavy object, while linus was getting his diaper changed is not an "obscure feature."

a five year old took his first aware car ride, and at a gas station saw the trunk of the car next to theirs open. he said "seriously, bmw has too many obscure features." after all, a car for him was where you put the baby seat. and why would you put that in a compartment with no windows or air, that's too small to even fit a baby seat.

did you enjoy the ride?

Re: Help Message for Shell Scripts

#105

Post by andsens »

My time to shine! I built an argument parser that uses a POSIX compliant help message as the input. It's a parser generator really. It generates minified bash that is inlined in your script, so no dependencies. The work is based off of docopt (and is docopt compliant). Check it out: https://github.com/andsens/docopt.sh

Re: Help Message for Shell Scripts

#106

Post by ChAns0n »

hansdieter1337 wrote: post #74

Even better: Don’t use bash. I started using Python instead of bash. It’s way better to read and more maintainable. If I need the performance of native-Unix commands, I can still use them using subprocess.

Python is not as handy/efficient as bash when you want to utilize some existing Unix commands. And normally it’s crucial to stop bleeding fast if something bad is happened to you server/cluster

Re: Help Message for Shell Scripts

#108

Post by GordonS »

pavon wrote: post #59
adrianmonk wrote: post #5

You can also use a "here document" help() { cat Options: Input file to read. Output file to write. Use '-' for stdout. -h Show this message. EOH } If the indentation bugs you, you can use a simpler sed trick to remove leading space so that you can indent it as desired: help() { sed -e 's/ //' Options: Input file to read. Output file to write. Use '-' for stdout. -h Show this message. EOH }

Or just a multiline string: #!/bin/bash USAGE="my-script — does one thing well Usage: my-script Options: Input file to read. Output file to write. Use '-' for stdout. -h Show this message. " help() { echo "$USAGE" } This is my standard approach which is cleaner for putting the documentation at the very top of the file like the linked article.

Woah, I had no idea multiline strings were even a thing in Bash, I've been using heredocs for help messages since forever!

Do you know if these are portable?

Re: Help Message for Shell Scripts

#109

Post by flaxton »

gfosco wrote: post #56
flaxton wrote: post #53

Didn't work on macOS (multiple sed errors - switches differ from Linux) but prompted me to write a help function ;-)

I have a project that makes heavy use of sed.. On macOS, I `brew install gnu-sed` and use `gsed` instead, so it works like other platforms.

Nice! I will check that out.

Re: Help Message for Shell Scripts

#110

Post by Anthony-G »

pavon wrote: post #59
adrianmonk wrote: post #5

You can also use a "here document" help() { cat Options: Input file to read. Output file to write. Use '-' for stdout. -h Show this message. EOH } If the indentation bugs you, you can use a simpler sed trick to remove leading space so that you can indent it as desired: help() { sed -e 's/ //' Options: Input file to read. Output file to write. Use '-' for stdout. -h Show this message. EOH }

Or just a multiline string: #!/bin/bash USAGE="my-script — does one thing well Usage: my-script Options: Input file to read. Output file to write. Use '-' for stdout. -h Show this message. " help() { echo "$USAGE" } This is my standard approach which is cleaner for putting the documentation at the very top of the file like the linked article.

That's exactly what I do. For others who were not aware that multi-line strings can be used, this is POSIX-compatible (most of my shell scripts are executed by `dash`).
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