Tips on how to create awesome command-line tools
Any tool that you expect other people to use should accept both short (-o) and long (--long-option) options. Arguments and options should be accepted in any order if possible.
Your tool should have help and completions for common shells; These should be always up to date with the actual options of the tool.
Why? Tools should save effort and time. Providing expected behaviour and completions saves time.
Writing and maintianing this is not fun and takes time. Luckily there are libraries that provide all this. Find a good one. Switch languages if yours does not have one. I'm serious - not providing completions because it is hard in a language you chose to use is idiotic. You owe good --help and completions to your users. This alone is a reason why you should not write serious command-line tools in bash.
Go: https://github.com/spf13/cobra
Python: https://docs.python.org/3/library/argparse.html
Do you plan to distribute your tool outside of standard package management? If so then the fewer dependencies the better. Can you bundle something with the tool instead of depending on it? Consider doing so.
Choose the right language for the job; Go compiles into statically linked binaries without dependencies. In contrast, bash has little builtin functionality and relies on various programs that might not be available on all systems.
If you can't avoid dependencies check if they are installed during installatoin and instruct the user to install them.
Green does not have a great contrast ratio.
In many terminal themes the contrast is insufficient which results in unreadable text.
For example, check out the color tool for material design: https://material.io/resources/color/#!/?view.left=1&view.right=0&primary.color=64DD17
Example of tool that breaks this tip is tig.
If you are making a teminal application (think ncurses) read this: Terminals Are Weird
Read this for extra credit: Stdout Buffering