Manual: run0
RUN0(1) run0 RUN0(1)
NAME
run0 - Elevate privileges
SYNOPSIS
run0 [OPTIONS...] [COMMAND...]
DESCRIPTION
run0 may be used to temporarily and interactively acquire elevated or different privileges. It serves a similar
purpose as sudo(8), but operates differently in a couple of key areas:
• No execution or security context credentials are inherited from the caller into the invoked commands, as they are
invoked from a fresh, isolated service forked off by the service manager.
• Authentication takes place via polkit[1], thus isolating the authentication prompt from the terminal (if
possible).
• An independent pseudo-tty is allocated for the invoked command, detaching its lifecycle and isolating it for
security.
• No SetUID/SetGID file access bit functionality is used for the implementation.
Altogether this should provide a safer and more robust alternative to the sudo mechanism, in particular in OS
environments where SetUID/SetGID support is not available (for example by setting the NoNewPrivileges= variable in
systemd-system.conf(5)).
Any session invoked via run0 will run through the "systemd-run0" PAM stack.
Note that run0 is implemented as an alternative multi-call invocation of systemd-run(1). That is, run0 is a symbolic
link to systemd-run executable file, and it behaves as run0 if it is invoked through the symbolic link, otherwise
behaves as systemd-run.
OPTIONS
The following options are understood:
--unit=
Use this unit name instead of an automatically generated one.
Added in version 256.
--property=
Sets a property of the service unit that is created. This option takes an assignment in the same format as
systemctl(1)'s set-property command.
Added in version 256.
--description=
Provide a description for the service unit that is invoked. If not specified, the command itself will be used as
a description. See Description= in systemd.unit(5).
Added in version 256.
--slice=
Make the new .service unit part of the specified slice, instead of user.slice.
Added in version 256.
--slice-inherit
Make the new .service unit part of the slice the run0 itself has been invoked in. This option may be combined
with --slice=, in which case the slice specified via --slice= is placed within the slice the run0 command is
invoked in.
Example: consider run0 being invoked in the slice foo.slice, and the --slice= argument is bar. The unit will then
be placed under foo-bar.slice.
Added in version 256.
--user=, -u, --group=, -g
Switches to the specified user/group. If not specified defaults to "root", unless --area= or --empower are used
(see below), in which case this defaults to the invoking user.
Added in version 256.
--nice=
Runs the invoked session with the specified nice level.
Added in version 256.
--chdir=, -D
Runs the invoked session with the specified working directory. If not specified defaults to the client's current
working directory if switching to the root user, or the target user's home directory otherwise.
Added in version 256.
--via-shell
Invokes the target user's login shell and runs the specified command (if any) via it.
Added in version 258.
-i
Shortcut for --via-shell --chdir='~'.
Added in version 258.
--setenv=NAME[=VALUE]
Runs the invoked session with the specified environment variable set. This parameter may be used more than once
to set multiple variables. When "=" and VALUE are omitted, the value of the variable with the same name in the
invoking environment will be used.
Added in version 256.
--background=COLOR
Change the terminal background color to the specified ANSI color as long as the session lasts. If not specified,
the background will be tinted in a reddish tone when operating as root, and in a yellowish tone when operating
under another UID, as reminder of the changed privileges. The color specified should be an ANSI X3.64 SGR
background color, i.e. strings such as "40", "41", ..., "47", "48;2;...", "48;5;...". See ANSI Escape Code
(Wikipedia)[2] for details. Set to an empty string to disable.
Example: "--background=44" for a blue background.
Added in version 256.
--pty, --pty-late, --pipe
Request allocation of a pseudo TTY for the run0 session (in case of --pty or --pty-late), or request passing the
caller's STDIO file descriptors directly through (in case of --pipe). --pty-late is very similar to --pty but
begins the TTY processing only once unit startup is complete, leaving input to any passwords/polkit agents until
that time. If neither switch is specified, or if both --pipe and one of --pty/--pty-late are specified, the mode
will be picked automatically: if standard input, standard output, and standard error output are all connected to
a TTY then a pseudo TTY is allocated (in --pty-late mode unless --no-ask-password is specified in which case
--pty is selected), otherwise the relevant file descriptors are passed through directly.
--pty and --pipe were added in v257.
--pty-late was added in v258.
--shell-prompt-prefix=STRING
Set a shell prompt prefix string. This ultimately controls the $SHELL_PROMPT_PREFIX environment variable for the
invoked program, which is typically imported into the shell prompt. By default – if emojis are supported –, a
superhero emoji is shown (🦸). This default may also be changed (or turned off) by passing the
$SYSTEMD_RUN_SHELL_PROMPT_PREFIX environment variable to run0, see below. Set to an empty string to disable shell
prompt prefixing.
Added in version 257.
--lightweight=BOOLEAN
Controls whether to activate the per-user service manager for the target user. By default if the target user is
"root" or a system user the per-user service manager is not activated as effect of the run0 invocation, otherwise
it is.
This ultimately controls the $XDG_SESSION_CLASS environment variable pam_systemd(8) respects.
Added in version 258.
--area=AREA
Controls the "area" of the target account to log into. Areas are secondary home directories within the primary
home directory of the target user, i.e. logging into area "foobar" of an account translates to $HOME being set to
~/Areas/foobar on login.
If this option is used, the default user to transition to changes from root to the calling user's (but --user=
takes precedence, see above). Or in other words, just specifying an area without a user is a mechanism to create
a new session of the calling user, just with a different area.
This ultimately controls the $XDG_AREA environment variable pam_systemd(8) respects.
For details on the area concept see pam_systemd_home(8).
Added in version 258.
--empower
If specified, run0 will elevate the privileges of the selected user (using --user=) or the current user if no
user is explicitly selected. Currently this means we give the invoked process all available capabilities and add
the "empower" group as a supplemental group (for which all polkit actions are allowed by default), but other
privileges may be granted in the future as well when using this option.
Note that other (unprivileged) processes of the selected user will have privileges over the invoked process.
Consider not using this option in an environment where there might be malicious processes running as the selected
user.
Added in version 259.
--same-root-dir
Execute the run0 session in the same root directory that the run0 command is executed in.
Added in version 259.
--machine=
Execute operation in a local container. Specify a container name to connect to.
Added in version 256.
--no-ask-password
Do not query the user for authentication for privileged operations.
-h, --help
Print a short help text and exit.
--version
Print a short version string and exit.
All command line arguments after the first non-option argument become part of the command line of the launched
process. If no command line is specified an interactive shell is invoked. The shell to invoke may be controlled
through --via-shell - when specified the target user's shell is used - or --setenv=SHELL=.... By default, the
originating user's shell is executed if operating locally, or /bin/sh when operating with --machine=.
Note that unlike sudo, run0 always spawns shells with login shell semantics, regardless of -i.
EXIT STATUS
On success, 0 is returned. If run0 failed to start the session or the specified command fails, a non-zero return
value will be returned.
ENVIRONMENT VARIABLES
As with systemd-run, the session will inherit the system environment from the service manager. In addition, the
following environment variables will be set:
$TERM
Copied from the $TERM of the caller. Can be overridden with --setenv=
Added in version 256.
$SUDO_USER
Set to the username of the originating user.
Added in version 256.
$SUDO_UID
Set to the numeric UNIX user id of the originating user.
Added in version 256.
$SUDO_GID
Set to the primary numeric UNIX group id of the originating session.
Added in version 256.
$SHELL_PROMPT_PREFIX
By default, set to the superhero emoji (if supported), but may be overridden with the
$SYSTEMD_RUN_SHELL_PROMPT_PREFIX environment variable (see below), or the --shell-prompt-prefix= switch (see
above).
Added in version 257.
The following variables may be passed to run0:
$SYSTEMD_RUN_SHELL_PROMPT_PREFIX
If set, overrides the default shell prompt prefix that run0 sets for the invoked shell (the superhero emoji). Set
to an empty string to disable shell prompt prefixing.
Added in version 257.
SEE ALSO
systemd(1), systemd-run(1), sudo(8), machinectl(1), pam_systemd(8)
NOTES
1. polkit
https://www.freedesktop.org/wiki/Software/polkit
2. ANSI Escape Code (Wikipedia)
https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_(Select_Graphic_Rendition)_parameters
systemd 259.5 RUN0(1)