Comment by pdkl95

A few additions to these recommendations:

> Show full help when -h and --help is passed

It is also a good idea to support --version

    $ make --version
    GNU Make 4.1
    Built for x86_64-pc-linux-gnu
    Copyright (C) 1988-2014 Free Software Foundation, Inc.
    License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
    This is free software: you are free to change and redistribute it.
    There is NO WARRANTY, to the extent permitted by law.

> Use standard names for flags, if there is a standard.

In the interest of consistency across tools, I recommend consulting the Table of Long Options from the GNU Coding Standards.

https://www.gnu.org/prep/standards/html_node/Option-Table.ht...

Some long options that are particularly helpful, when appropriate:

    ‘dry-run’
         ‘-n’ in make.

    ‘null’
        ‘-0’ in xargs.

Also, options that increase safety:

    'no-clobber'
        ‘-n’ in mv
        # do not overwrite an existing file

    'overwrite'
        ‘-c’ in unshar
        # even better than --no-clobber, require explicit
        # permission before overwriting existing files

edit:

Never try to be "smart" or "magic" and guess what the user intended! DWIM can appear useful at first, but we've known for a long time that DWIM behavior is dangerous[1].

[1] https://news.ycombinator.com/item?id=15628014