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

       -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.

       -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.

       -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.)

       -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/>.