问题
Am wondering if this question is already addressed or not.
I have used few commands like this :
npm install -g
npm install -d
Then i have used few like :
npm install XYZ --save-dev
npm install --only=dev
Whats the fundamental difference between - and -- ?
Has it got to do anything with primary and secondary arguments ?
回答1:
No, it's simply that by convention, *nix command line switches that are only one dash (-d) are only one character. Those with two dashes (--save) are multiple characters long. Both are optional.
回答2:
See https://serverfault.com/questions/387935/whats-the-difference-betwen-the-single-dash-and-double-dash-flags-on-shell-comm
Basically, a single dash means that the following flags are single-character only, and generally means that more than one flag can be passed. See all other command line tools:
ls -la
grep -inr "asd" .
etc
The double dash connotes a single positional flag/argument to a command line tool.
回答3:
Generally, - is an abbreviation, there must be a corresponding -— full name.
For example:
npm install -D is equal to npm install --save-dev
来源：https://stackoverflow.com/questions/44312256/difference-between-and-single-and-double-dash-in-npm-commands