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= is 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.
--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.
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.
