NAME

       runuser - run a command with substitute user and group ID

SYNOPSIS

       runuser [options] -u user [[--] command [argument...]]

       runuser [options] [-] [user [argument...]]

DESCRIPTION

       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 session management.

       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.

       Since version 2.38 runuser resets process resource limits RLIMIT_NICE, RLIMIT_RTPRIO,
       RLIMIT_FSIZE, RLIMIT_AS and RLIMIT_NOFILE.

OPTIONS

       -c, --command=command
           Pass command to the shell with the -c option.

       -f, --fast
           Pass -f to the shell, which may or may not be useful, depending on the shell.

       -g, --group=group
           The primary group to be used. This option is allowed for the root user only.

       -G, --supp-group=group
           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 directory

           •   sets argv[0] of the shell to '-' in order to make the shell a login shell

       -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.

       -P, --pty
           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 runuser works as a proxy between the sessions (sync 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.

       -s, --shell=shell
           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 target user

           •   /bin/sh

               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.

       --session-command=command
           Same as -c, but do not create a new session. (Discouraged.)

       -T, --no-pty*
           Do not create a pseudo-terminal, opposite of --pty and -P. Note that running without a
           pseudo-terminal opens the security risk of privilege escalation through
           TIOCSTI/TIOCLINUX ioctl command injection.

       -w, --whitelist-environment=list
           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.

       -h, --help
           Display help text and exit.

       -V, --version
           Print version and exit.

CONFIG FILES

       runuser reads the /etc/default/runuser and /etc/login.defs configuration files. The
       following configuration items are relevant for runuser:

       ENV_PATH (string)
           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 /usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin.

       ALWAYS_SET_PATH (boolean)
           If set to yes and --login and --preserve-environment were not specified runuser
           initializes PATH.

       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)).

EXIT STATUS

       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:

       1
           Generic error before executing the requested command

       126
           The requested command could not be executed

       127
           The requested command was not found

FILES

       /etc/pam.d/runuser
           default PAM configuration file

       /etc/pam.d/runuser-l
           PAM configuration file if --login is specified

       /etc/default/runuser
           runuser specific logindef config file

       /etc/login.defs
           global logindef config file

HISTORY

       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.

SEE ALSO

       setpriv(1), su(1), login.defs(5), shells(5), pam(8)

REPORTING BUGS

       For bug reports, use the issue tracker at https://github.com/util-linux/util-linux/issues.

AVAILABILITY

       The runuser command is part of the util-linux package which can be downloaded from Linux
       Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>.