mirror of
https://github.com/systemd/systemd.git
synced 2024-11-01 09:21:26 +03:00
99 lines
4.2 KiB
Markdown
99 lines
4.2 KiB
Markdown
# Known Environment Variables
|
|
|
|
A number of systemd components take additional runtime parameters via
|
|
environment variables. Many of these environment variables are not supported at
|
|
the same level as command line switches and other interfaces are: we don't
|
|
document them in the man pages and we make no stability guarantees for
|
|
them. While they generally are unlikely to be dropped any time soon again, we
|
|
do not want to guarantee that they stay around for good either.
|
|
|
|
Below is an (incomprehensive) list of the environment variables understood by
|
|
the various tools. Note that this list only covers environment variables not
|
|
documented in the proper man pages.
|
|
|
|
All tools:
|
|
|
|
* `$SYSTEMD_OFFLINE=[0|1]` — if set to `1`, then `systemctl` will
|
|
refrain from talking to PID 1; this has the same effect as the historical
|
|
detection of `chroot()`. Setting this variable to `0` instead has a similar
|
|
effect as `SYSTEMD_IGNORE_CHROOT=1`; i.e. tools will try to
|
|
communicate with PID 1 even if a `chroot()` environment is detected.
|
|
You almost certainly want to set this to `1` if you maintain a package build system
|
|
or similar and are trying to use a modern container system and not plain
|
|
`chroot()`.
|
|
|
|
* `$SYSTEMD_IGNORE_CHROOT=1` — if set, don't check whether being invoked in a
|
|
`chroot()` environment. This is particularly relevant for systemctl, as it
|
|
will not alter its behaviour for `chroot()` environments if set. Normally it
|
|
refrains from talking to PID 1 in such a case; turning most operations such
|
|
as `start` into no-ops. If that's what's explicitly desired, you might
|
|
consider setting `SYSTEMD_OFFLINE=1`.
|
|
|
|
* `$SD_EVENT_PROFILE_DELAYS=1` — if set, the sd-event event loop implementation
|
|
will print latency information at runtime.
|
|
|
|
* `$SYSTEMD_PROC_CMDLINE` — if set, may contain a string that is used as kernel
|
|
command line instead of the actual one readable from /proc/cmdline. This is
|
|
useful for debugging, in order to test generators and other code against
|
|
specific kernel command lines.
|
|
|
|
systemctl:
|
|
|
|
* `$SYSTEMCTL_FORCE_BUS=1` — if set, do not connect to PID1's private D-Bus
|
|
listener, and instead always connect through the dbus-daemon D-bus broker.
|
|
|
|
* `$SYSTEMCTL_INSTALL_CLIENT_SIDE=1` — if set, enable or disable unit files on
|
|
the client side, instead of asking PID 1 to do this.
|
|
|
|
* `$SYSTEMCTL_SKIP_SYSV=1` — if set, do not call out to SysV compatibility hooks.
|
|
|
|
systemd-nspawn:
|
|
|
|
* `$UNIFIED_CGROUP_HIERARCHY=1` — if set, force nspawn into unified cgroup
|
|
hierarchy mode.
|
|
|
|
* `$SYSTEMD_NSPAWN_API_VFS_WRITABLE=1` — if set, make /sys and /proc/sys and
|
|
friends writable in the container. If set to "network", leave only
|
|
/proc/sys/net writable.
|
|
|
|
* `$SYSTEMD_NSPAWN_CONTAINER_SERVICE=…` — override the "service" name nspawn
|
|
uses to register with machined. If unset defaults to "nspawn", but with this
|
|
variable may be set to any other value.
|
|
|
|
* `$SYSTEMD_NSPAWN_USE_CGNS=0` — if set, do not use cgroup namespacing, even if
|
|
it is available.
|
|
|
|
* `$SYSTEMD_NSPAWN_LOCK=0` — if set, do not lock container images when running.
|
|
|
|
systemd-logind:
|
|
|
|
* `$SYSTEMD_BYPASS_HIBERNATION_MEMORY_CHECK=1` — if set, report that
|
|
hibernation is available even if the swap devices do not provide enough room
|
|
for it.
|
|
|
|
installed systemd tests:
|
|
|
|
* `$SYSTEMD_TEST_DATA` — override the location of test data. This is useful if
|
|
a test executable is moved to an arbitrary location.
|
|
|
|
nss-systemd:
|
|
|
|
* `$SYSTEMD_NSS_BYPASS_SYNTHETIC=1` — if set, `nss-systemd` won't synthesize
|
|
user/group records for the `root` and `nobody` users if they are missing from
|
|
`/etc/passwd`.
|
|
|
|
* `$SYSTEMD_NSS_DYNAMIC_BYPASS=1` — if set, `nss-systemd` won't return
|
|
user/group records for dynamically registered service users (i.e. users
|
|
registered through `DynamicUser=1`).
|
|
|
|
* `$SYSTEMD_NSS_BYPASS_BUS=1` — if set, `nss-systemd` won't use D-Bus to do
|
|
dynamic user lookups. This is primarily useful to make `nss-systemd` work
|
|
safely from within `dbus-daemon`.
|
|
|
|
systemd-timedated:
|
|
|
|
* `$SYSTEMD_TIMEDATED_NTP_SERVICES=…` — colon-separated list of unit names of
|
|
NTP client services. If set, `timedatectl set-ntp on` enables and starts the
|
|
first existing unit listed in the environment variable, and
|
|
`timedatectl set-ntp off` disables and stops all listed units.
|