is there a way to write a command with lots of options in a more legible\maintainable script format?

Question

My question may not be clear enough, so here's a specific example.

I have an rsync bin\bash script with a ton of option switches.

Instead of:

rsync --recursive --times --update --chown=root,root --bwlimit=500

I'd like to be able to write my script like this:

rsync
--recursive 
--times 
--update 
--chown=root,root 
--bwlimit=500

That way, I can easily comment out or edit individual options if I need to.

Is there any way to do this?

Does this answer your question? Break a long command to multiple lines and related Shell Syntax: How to correctly use \ to break lines?. — αғsнιη, Jul 01 '20 at 17:35

terdon · Answer 1 · 2020-07-01T17:32:06.243

3

Yep. Just escape the end of line with a \. Like this:

rsync \
  --recursive \
  --times \
  --update \
  --chown=root,root \
  --bwlimit=500

The amount of whitespace is irrelevant, the important thing is having the \ as the last character. So you can even align them all nicely like this:

rsync               \
  --recursive       \
  --times           \
  --update          \
  --chown=root,root \
  --bwlimit=500

Note that there can be no whitespace (or anything else) after the \, it must be the last character.

edited Jul 01 '20 at 17:32

answered Jul 01 '20 at 17:28

terdon

I tried this.
Seems to do mostly what I want, but it seems it still doesn't allow you to easily comment out (or just comment) about particular lines.

For example, I'd like to be able to do rsync \ #--verbose \ --recursive and then be able to remove the comment on --verbose as needed, but it seems that # isn't really compatible with the \ continuation marker.
– Daniel Jul 03 '20 at 04:00

score 0 · Answer 2 · answered Jul 01 '20 at 17:34

0

Can't speak for other linux distributions but,

in RHEL/CentOS 7 I like creating

/etc/profile.d/myaliases.sh

and in your case would do

alias rsync2='rsync --recursive --times --update --chown=root,root --bwlimit=500'

change rsync2 to whatever you like, then all you need to do is type rsync2

answered Jul 01 '20 at 17:34

ron

Eeeek! Please don't! Use ~/.profile or ~/.bashrc for this, don't modify global files! That's more dangerous, more intrusive if you have multiple users and much harder to maintain across updates. That said, this is about using a command in scripts and making it more legible. Using an alias won't help, especially not if you define it in a file that isn't read by scripts. So this isn't really answering the question. – terdon Jul 02 '20 at 18:24
please look into what profile.d/ folder is about. This is not modifying global files. It is a simple alias. You could do this in your script as a local alias, or you could make it available to all by making use of profile.d. Or you could just be miserable and type it all out every time. I like typing less characters when possible. – ron Jul 04 '20 at 00:29
I know what it is, thank you. And as you said, that affects all users on a machine. That's what global means. If you want to set an alias, use your local files not global ones. It's safer, less intrusive and easier to maintain. But anyway, again, you're not answering the question here. Using an alias wouldn't work in a script (unless you explain how to enable them and make sure the script is executed in an anvironment that has read the profile files), so it isn't a way of formatting a long command. – terdon Jul 04 '20 at 12:58

2 Answers2