runuser - run a command with substitute user and group ID
runuser [options] -u user [[--] command
runuser [options] [-] [user
runuser can be used to run commands with a substitute user and group ID.
If the option -u is not given, runuser falls back to
su-compatible semantics and a shell is executed. The difference between
the commands runuser and su is that runuser does not ask
for a password (because it may be executed by the root user only) and it uses
a different PAM configuration. The command runuser does not have to be
installed with set-user-ID permissions.
If the PAM session is not required, then the recommended solution
is to use the setpriv(1) command.
When called without arguments, runuser defaults to running
an interactive shell as root.
For backward compatibility, runuser defaults to not
changing the current directory and to setting only the environment variables
HOME and SHELL (plus USER and LOGNAME if the
target user is not root). This version of runuser uses PAM for
Note that runuser in all cases use PAM (pam_getenvlist())
to do the final environment modification. Command-line options such as
--login and --preserve-environment affect the environment
before it is modified by PAM.
Pass command to the shell with the -c
Pass -f to the shell, which may or may not be
useful, depending on the shell.
The primary group to be used. This option is allowed for
the root user only.
Specify a supplementary group. This option is available
to the root user only. The first specified supplementary group is also used as
a primary group if the option --group is not specified.
-, -l, --login
Start the shell as a login shell with an environment
similar to a real login:
•clears all the environment variables except for
TERM and variables specified by --whitelist-environment
•initializes the environment variables
HOME, SHELL, USER, LOGNAME, and PATH
•changes to the target user’s home
•sets argv of the shell to '-' in order
to make the shell a login shell
Create a pseudo-terminal for the session. The independent
terminal provides better security as the user does not share a terminal with
the original session. This can be used to avoid TIOCSTI ioctl terminal
injection and other security attacks against terminal file descriptors. The
entire session can also be moved to the background (e.g., runuser --pty -u
username — command &
). If the pseudo-terminal is enabled, then
works as a proxy between the sessions (copy stdin and stdout).
This feature is mostly designed for interactive sessions. If the
standard input is not a terminal, but for example a pipe (e.g., echo
"date" | runuser --pty -u user), then the ECHO flag for the
pseudo-terminal is disabled to avoid messy output.
-m, -p, --preserve-environment
Preserve the entire environment, i.e., do not set
HOME, SHELL, USER or LOGNAME. The option is
ignored if the option --login is specified.
Run the specified shell
instead of the default.
The shell to run is selected according to the following rules, in order:
•the shell specified with --shell
•the shell specified in the environment variable
SHELL if the --preserve-environment option is used
•the shell listed in the passwd entry of the
If the target user has a restricted shell (i.e., not listed in
/etc/shells), then the --shell option and the SHELL
environment variables are ignored unless the calling user is root.
Same as -c, but do not create a new session.
Don’t reset the environment variables specified in
the comma-separated list when clearing the environment for
--login. The whitelist is ignored for the environment variables
HOME, SHELL, USER, LOGNAME, and PATH.
Display version information and exit.
Display help text and exit.
runuser reads the /etc/default/runuser and /etc/login.defs
configuration files. The following configuration items are relevant for
Defines the PATH environment variable for a regular user.
The default value is /usr/local/bin:/bin:/usr/bin.
ENV_ROOTPATH (string), ENV_SUPATH (string)
Defines the PATH environment variable for root.
ENV_SUPATH takes precedence. The default value is
If set to yes and --login and
--preserve-environment were not specified runuser initializes
The environment variable PATH may be different on systems
where /bin and /sbin are merged into /usr; this
variable is also affected by the --login command-line option and the
PAM system setting (e.g., pam_env(8)).
runuser normally returns the exit status of the command it executed. If
the command was killed by a signal, runuser returns the number of the
signal plus 128.
Exit status generated by runuser itself:
Generic error before executing the requested
The requested command could not be executed
The requested command was not found
default PAM configuration file
PAM configuration file if --login is
runuser specific logindef config file
global logindef config file
This runuser command was derived from coreutils' su, which was
based on an implementation by David MacKenzie, and the Fedora runuser
command by Dan Walsh.