SIGTERM
Upon receiving this signal the systemd system manager
serializes its state, reexecutes itself and deserializes the
saved state again. This is mostly equivalent to systemctl
daemon-reexec.
systemd user managers will start the exit.target unit when
this signal is received. This is mostly equivalent to
systemctl --user start exit.target
--job-mode=replace-irreversibly.
SIGINT
Upon receiving this signal the systemd system manager will
start the ctrl-alt-del.target unit. This is mostly equivalent
to systemctl start ctrl-alt-del.target
--job-mode=replace-irreversibly. If this signal is received
more than 7 times per 2s, an immediate reboot is triggered.
Note that pressing Ctrl+Alt+Del on the console will trigger
this signal. Hence, if a reboot is hanging, pressing
Ctrl+Alt+Del more than 7 times in 2 seconds is a relatively
safe way to trigger an immediate reboot.
systemd user managers treat this signal the same way as
SIGTERM.
SIGWINCH
When this signal is received the systemd system manager will
start the kbrequest.target unit. This is mostly equivalent to
systemctl start kbrequest.target.
This signal is ignored by systemd user managers.
SIGPWR
When this signal is received the systemd manager will start
the sigpwr.target unit. This is mostly equivalent to
systemctl start sigpwr.target.
SIGUSR1
When this signal is received the systemd manager will try to
reconnect to the D-Bus bus.
SIGUSR2
When this signal is received the systemd manager will log its
complete state in human-readable form. The data logged is the
same as printed by systemd-analyze dump.
SIGHUP
Reloads the complete daemon configuration. This is mostly
equivalent to systemctl daemon-reload.
SIGRTMIN+0
Enters default mode, starts the default.target unit. This is
mostly equivalent to systemctl isolate default.target.
SIGRTMIN+1
Enters rescue mode, starts the rescue.target unit. This is
mostly equivalent to systemctl isolate rescue.target.
SIGRTMIN+2
Enters emergency mode, starts the emergency.service unit.
This is mostly equivalent to systemctl isolate
emergency.service.
SIGRTMIN+3
Halts the machine, starts the halt.target unit. This is
mostly equivalent to systemctl start halt.target
--job-mode=replace-irreversibly.
SIGRTMIN+4
Powers off the machine, starts the poweroff.target unit. This
is mostly equivalent to systemctl start poweroff.target
--job-mode=replace-irreversibly.
SIGRTMIN+5
Reboots the machine, starts the reboot.target unit. This is
mostly equivalent to systemctl start reboot.target
--job-mode=replace-irreversibly.
SIGRTMIN+6
Reboots the machine via kexec, starts the kexec.target unit.
This is mostly equivalent to systemctl start kexec.target
--job-mode=replace-irreversibly.
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.
