systemd менеджер по системе и сервису (systemd system and service manager)
SOCKETS AND FIFOS
/run/systemd/notify
Daemon status notification socket. This is an AF_UNIX
datagram socket and is used to implement the daemon
notification logic as implemented by sd_notify(3).
/run/systemd/private
Used internally as communication channel between systemctl(1)
and the systemd process. This is an AF_UNIX
stream socket.
This interface is private to systemd and should not be used
in external projects.
/dev/initctl
Limited compatibility support for the SysV client interface,
as implemented by the systemd-initctl.service unit. This is a
named pipe in the file system. This interface is obsolete and
should not be used in new applications.