RUNUSER
Section: User Commands (1)
Updated: July 2014
Page Index
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.
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 (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.
- -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.
- -V, --version
-
Display version information and exit.
- -h, --help
-
Display help text 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)
AVAILABILITY
The runuser command is part of the util-linux package and is
available from
Linux Kernel Archive