Hey I want to add a command to my system. I am not using any package-format or anything. I just want to install a script that I wrote.

I know of some ways to do that:

• add my script into whatever is the first thing in $PATH
• add a custom path to $PATH (in /etc/profile.d/ or /etc/environment) and put the script into the custom path
• add my script into /usr/bin or /usr/local/bin

I remember reading that profile.d/ doesn’t get picked up by all shells and that /etc/environment (which exists but is empty on my system) shouldn’t be used.

What should I do to ensure that my command will be available everywhere on any gnu/linux or bsd system?

EDIT: I should clarify that I am asking this only out of curiosity. I just like knowing how this stuff works. The script was just an example (I thought this would make it easier to understand, lol). I am interested in knowing a way to install a command without any chance of that command later not being found by other programs. I find many different answers to this and they all seem a little muddy, like “doing x should usually work”. I want to know the solution that always works