su - Substitutes user ID temporarily
su [-|-f] [user] [shell_option] [shell_command]
Prevents the user's shell initialization file from being executed
by passing the
option to the
shell, thus making
start up faster. The
option is supported by the
family of shells.
Simulates a full login by executing the commands in either
and by setting the current working directory to
user's home directory.
Passes the specified shell option flag to the newly invoked
user's shell for execution. The
be supported by the invoked shell. The
ksh, and any other interactive command shell
support the commonly used
shell option. By default (no ``shell_option''), the shell is opened with the
(interactive) shell option. See the reference page for the shell
you are using for more information on the shell options.
Passes the specified command to the newly invoked user's shell
for execution. The
must be supported
by the invoked shell.
The su command demands the password of the specified user, and if it is given, changes to that user and invokes the user's shell without changing the current directory.
Except in a case where the - option is used, the user environment is unchanged except for HOME, SHELL, USER, and LOGNAME which are taken from the password file for the user being substituted (see environ). The new user ID stays in force until the shell exits.
If no user is specified, root is assumed. Only users who belong to group number 0 (system) can issue su to become root, even with the root password. To remind superusers of their responsibilities, the shell substitutes a # (number sign) for its usual prompt.
Shell commands may be passed to the shell that is spawned by
by including them on the command line after the
flags and arguments. After the flags recognized by
argument are processed, unrecognized command
line flags (shell_options) and/or arguments (shell_commands) are passed to the shell for execution. If the
spawned shell does not support the command or the format of the command, the
command is not executed and the resulting shell behavior and error messages
are determined by the shell.
command fails if any lock conditions exist
on the target account. Specifically, if the destination account was retired,
if the number of unsuccessful login attempts exceeds the maximum allowed,
if the administrative lock was applied, or the password's lifetime was exceeded,
the Information System Security Officer (ISSO) must unlock the destination
account before any user can log in to it or use
This security-sensitive command uses SIA (Security Integration Architecture)
as an interface to the security mechanism(s) that perform the actual user
validation. See the
reference page for more information.
Commands: csh(1), ksh(1), sh(1)