* `$SD_EVENT_PROFILE_DELAYS=1` — if set, the sd-event event loop implementation
will print latency information at runtime.
+* `$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:
* `$SYSTEMCTL_FORCE_BUS=1` — if set, do not connect to PID1's private D-Bus
* `$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`.