In my experience, i had never actually stumbled upon a formal list of these "GNU rules", the closest thing i can find is this: https://www.gnu.org/software/libc

In my experience, i had never actually stumbled upon a formal list of these "GNU rules", the closest thing i can find is this: https://www.gnu.org/software/libc/manual/html_node/Argument-Syntax.html https://www.gnu.org/software/libc/manual/html_node/Argument-... However, even those seem to raise some questions, for example: > To make command line even more confusing, multiple tools I have used allow spaces in optional arguments (e.g. "-opt1 arg1 arg2 -opt2", where arg1 and arg2 set two values for -opt1). Is described as something that's permissible: > An option and its argument may or may not appear as separate tokens. (In other words, the whitespace separating them is optional.) Thus, ‘-o foo’ and ‘-ofoo’ are equivalent. Therefore the below would be considered equivalent: -opt1 arg1 arg2 -opt2 -opt1arg1arg2 -opt2 Were your expectations different? Are there any good articles on the benefits of following such rules (any fungible improvements to legibility or usability, as opposed to just "consistency amongst different tools")? Are there any tools which can validate whether any piece of software conforms to this standard (either by scanning the man pages, or the code, or a formalized format of parameters the app supports)? Personally, the closest i've found is Typer ( https://typer.tiangolo.com/ https://typer.tiangolo.com/ ) but without anything that can automatically reject non-conformant code as a part of a CI process, i think enforcing such formats would be a non-starter for me.