diff --git a/man/common-variables.xml b/man/common-variables.xml
index 809a9084a21..b875e38d394 100644
--- a/man/common-variables.xml
+++ b/man/common-variables.xml
@@ -7,6 +7,79 @@
Environment
+
+ $SYSTEMD_LOG_LEVEL
+
+ The maximum log level of emitted messages (messages with a higher log level, i.e. less
+ important ones, will be suppressed). Either one of (in order of decreasing importance)
+ emerg, alert, crit,
+ err, warning, notice,
+ info, debug, or an integer in the range 0…7. See
+ syslog3
+ for more information.
+
+
+
+
+ $SYSTEMD_LOG_COLOR
+
+ A boolean. If true, messages written to the tty will be colored according to
+ priority.
+
+ This setting is only useful when messages are written directly to the terminal, because
+ journalctl1 and
+ other tools that display logs will color messages based on the log level on their own.
+
+
+
+
+ $SYSTEMD_LOG_TIME
+
+ A boolean. If true, log messages will be prefixed with a timestamp.
+
+ This setting is only useful when messages are written directly to the terminal or a file, because
+ journalctl1 and
+ other tools that display logs will attach timestamps based on the entry metadata on their own.
+
+
+
+
+ $SYSTEMD_LOG_LOCATION
+
+ A boolean. If true, messages will be prefixed with a filename and line number
+ in the source code where the message originates.
+
+ Note that the log location is often attached as metadata to journal entries anyway. Including it
+ directly in the message text can nevertheless be convenient when debugging programs.
+
+
+
+
+ $SYSTEMD_LOG_TID
+
+ A boolean. If true, messages will be prefixed with the current numerical thread ID
+ (TID).
+
+ Note that the this information is attached as metadata to journal entries anyway. Including it
+ directly in the message text can nevertheless be convenient when debugging programs.
+
+
+
+
+ $SYSTEMD_LOG_TARGET
+
+ The destination for log messages. One of console (log to the
+ attached tty), console-prefixed (log to the attached tty but with prefixes
+ encoding the log level and "facility", see syslog3,
+ kmsg (log to the kernel circular log buffer), journal (log to
+ the journal), journal-or-kmsg (log to the journal if available, and to kmsg
+ otherwise), auto (dermine the appropriate log target automatically, the default),
+ null (disable log output).
+
+
+
+
+
+
+
+
+