Please refer to the Filesystem Hierarchy Standard (FHS) for Linux for this.

• /bin : For binaries usable before the /usr partition is mounted. This is used for trivial binaries used in the very early boot stage or ones that you need to have available in booting single-user mode. Think of binaries like cat, ls, etc.




• /sbin : Same, but for binaries with superuser (root) privileges required.




• /usr/bin : Same as first, but for general system-wide binaries.




• /usr/sbin : Same as above, but for binaries with superuser (root) privileges required.

if I'm writing my own scripts, where should I add these?

None of the above. You should use /usr/local/bin or /usr/local/sbin for system-wide available scripts. The local path means it's not managed by the system packages (this is an error for Debian/Ubuntu packages).

For user-scoped scripts, use ~/bin (a personal bin folder in your home directory).

The FHS says for /usr/local:

Tertiary hierarchy for local data, specific to this host. Typically has further subdirectories, e.g., bin/, lib/, share/.