SU(1) BSD General Commands Manual SU(1)NAMEsu — substitute user identity
SYNOPSISsu [-flm] [login] [-c shell arguments]
DESCRIPTIONsu requests the password for login and switches to that user and group ID
after obtaining proper authentication. A shell is then executed, and any
additional shell arguments after the login name are passed to the shell.
If su is executed by root, no password is requested and a shell with the
appropriate user ID is executed.
The options are as follows:
-c Invoke the following command in a subshell as the specified user.
-f If the invoked shell is csh(1), this option prevents it from
reading the “.cshrc” file.
-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. This option is
identical to just passing "-", as in "su -".
-m Leave the environment unmodified. The invoked shell is your
login shell, and no directory changes are made. As a security
precaution, if the target user's shell is a non-standard shell
(as defined by getusershell(3)) and the caller's real uid is non-
zero, su will fail.
The -l and -m options are mutually exclusive; the last one specified
overrides any previous ones.
Only users in group “wheel” (normally gid 0) or group “admin” (normally
gid 20) can su to “root”.
By default (unless the prompt is reset by a startup file) the super-user
prompt is set to “#” to remind one of its awesome power.
SEE ALSOcsh(1), login(1), sh(1), skey(1), kinit(1), kerberos(1), passwd(5),
Environment variables used by su :
HOME Default home directory of real user ID unless modified as specified
PATH Default search path of real user ID unless modified as specified
TERM Provides terminal type which may be retained for the substituted
USER The user ID is always the effective ID (the target user ID) after
an su unless the user ID is 0 (root).
A su command appeared in Version 7 AT&T UNIX.
BSD April 18, 1994 BSD