Linux – Path difference between ../ and ./

There is little difference in the command pairs you are wondering about.

The first pair attempts to simulate a fresh login as the new user-- there could be some difference in the environmental variables supplied, as sudo su - is going to try and preserve existing environmental variables, while sudo -i will set very specific environmental variables and strip all others (check your man pages for specifics).

For the second pair, the difference in behavior is this: sudo su will always start the shell listed in the user's /etc/passwd, whereas sudo -s will check the SHELL environmental variable first, and only execute the shell in /etc/passwd if SHELL is unset.

The difference between "-" and "no hyphen" is that the latter keeps your existing environment (variables, etc); the former creates a new environment (with the settings of the actual user, not your own).

https://wiki.archlinux.org/index.php/Su

The hyphen has two effects:

1) switches from the current directory to the home directory of the new user (e.g., to /root in the case of the root user) by logging in as that user

2) changes the environmental variables to those of the new user as dictated by their ~/.bashrc. That is, if the first argument to su is a hyphen, the current directory and environment will be changed to what would be expected if the new user had actually logged on to a new session (rather than just taking over an existing session).