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7th chunk of `systemd.man`
73236684936204053e3f4f032f8ec153c60aa07f995679650000000100000fad
 SIGRTMIN+13
           Immediately halts the machine.

       SIGRTMIN+14
           Immediately powers off the machine.

       SIGRTMIN+15
           Immediately reboots the machine.

       SIGRTMIN+16
           Immediately reboots the machine with kexec.

       SIGRTMIN+20
           Enables display of status messages on the console, as controlled via
           systemd.show_status=1 on the kernel command line.

       SIGRTMIN+21
           Disables display of status messages on the console, as controlled
           via systemd.show_status=0 on the kernel command line.

       SIGRTMIN+22
           Sets the service manager's log level to "debug", in a fashion
           equivalent to systemd.log_level=debug on the kernel command line.

       SIGRTMIN+23
           Restores the log level to its configured value. The configured value
           is derived from – in order of priority – the value specified with
           systemd.log-level= on the kernel command line, or the value
           specified with LogLevel= in the configuration file, or the built-in
           default of "info".

       SIGRTMIN+24
           Immediately exits the manager (only available for --user instances).

       SIGRTMIN+25
           Upon receiving this signal the systemd manager will reexecute
           itself. This is mostly equivalent to systemctl daemon-reexec except
           that it will be done asynchronously.

           The systemd system manager treats this signal the same way as
           SIGTERM.

       SIGRTMIN+26
           Restores the log target to its configured value. The configured
           value is derived from – in order of priority – the value specified
           with systemd.log-target= on the kernel command line, or the value
           specified with LogTarget= in the configuration file, or the built-in
           default.

       SIGRTMIN+27, SIGRTMIN+28
           Sets the log target to "console" on SIGRTMIN+27 (or "kmsg" on
           SIGRTMIN+28), in a fashion equivalent to systemd.log_target=console
           (or systemd.log_target=kmsg on SIGRTMIN+28) on the kernel command
           line.

ENVIRONMENT
       The environment block for the system manager is initially set by the
       kernel. (In particular, "key=value" assignments on the kernel command
       line are turned into environment variables for PID 1). For the user
       manager, the system manager sets the environment as described in the
       "Environment Variables in Spawned Processes" section of systemd.exec(5).
       The DefaultEnvironment= setting in the system manager applies to all
       services including user@.service. Additional entries may be configured
       (as for any other service) through the Environment= and EnvironmentFile=
       settings for user@.service (see systemd.exec(5)). Also, additional
       environment variables may be set through the ManagerEnvironment= setting
       in systemd‐system.conf(5) and systemd‐user.conf(5).

       Some of the variables understood by systemd:

       $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
           syslog(3) for more information.

           This can be overridden with --log-level=.

       $SYSTEMD_LOG_COLOR
           A boolean. If true, messages written to the tty will be colored
           according to priority.

           This can be overridden with --log-color=.

       $SYSTEMD_LOG_TIME
           A boolean. If true, console log messages will be prefixed with a
           timestamp.

           This can be overridden with --log-time=.

       $SYSTEMD_LOG_LOCATION
           A boolean. If true, messages will be prefixed with a filename and
           line number in the source code
Title: Systemd Signal Handling and Environment Variables
Summary
This section continues detailing how systemd responds to specific SIGRTMIN signals, including immediate halt, power off, reboot, kexec, enabling/disabling status messages, setting/restoring log level and target. It also covers exiting the user manager, re-executing the manager, and setting the log target to console/kmsg. The section then transitions to environment variables understood by systemd, such as SYSTEMD_LOG_LEVEL, SYSTEMD_LOG_COLOR, SYSTEMD_LOG_TIME, and SYSTEMD_LOG_LOCATION, which control log message verbosity, color, timestamps, and source code location.