De sudo manual geeft hiervoor:
SYNOPSIS
sudo -h | -K | -k | -L | -V
sudo -v [-AknS] [-g group name | #gid] [-p prompt] [-u user name | #uid]
sudo -l[l] [-AknS] [-g group name | #gid] [-p prompt] [-U user name] [-u user name | #uid] [command]
sudo [-AbEHnPS] [-C fd] [-g group name | #gid] [-p prompt] [-u user name | #uid] [VAR=value] -i | -s [command]
sudoedit [-AnS] [-C fd] [-g group name | #gid] [-p prompt] [-u user name | #uid] file ...
DESCRIPTION
-i [command]
The -i (simulate initial login) option runs the shell
specified by the password database entry of the target
user as a login shell. This means that login-specific
resource files such as .profile or .login will be read
by the shell. If a command is specified, it is passed
to the shell for execution via the shell's -c option.
If no command is specified, an interactive shell is
executed. sudo attempts to change to that user's home
directory before running the shell. It also
initializes the environment to a minimal set of
variables, similar to what is present when a user logs
in. The Command environment section below documents in
detail how the -i option affects the environment in
which a command is run.
SYNOPSIS
su [-] [-flm] [login [args]]
DESCRIPTION
The su utility requests appropriate user credentials via PAM and switches to that user ID (the default user is the superuser).
A shell is then executed.
PAM is used to set the policy su(1) will use. In particular, by default only users in the ``admin'' or ``wheel'' groups can
switch to UID 0 (``root''). This group requirement may be changed by modifying the ``pam_group'' section of /etc/pam.d/su.
See pam_group(8) for details on how to modify this setting.
By default, the environment is unmodified with the exception of USER, HOME, and SHELL. HOME and SHELL are set to the target
login's default values. USER is set to the target login, unless the target login has a user ID of 0, in which case it is
unmodified. The invoked shell is the one belonging to the target login. This is the traditional behavior of su.
The options are as follows:
-l Simulate a full login. The environment is discarded except for HOME, SHELL, PATH, TERM, and USER. HOME and SHELL are
modified as above. USER is set to the target login. PATH is set to ``/bin:/usr/bin''. TERM is imported from your
current environment. The invoked shell is the target login's, and su will change directory to the target login's home
directory.
- (no letter) The same as -l.