INIT(1M)                             SysV                             INIT(1M)



NAME
     init - process control initialization

SYNOPSIS
     /etc/init

DESCRIPTION
     init is invoked as the last step in the boot procedure.  It normally runs
     the automatic reboot sequence, and if this succeeds, begins multi-user
     operation.

     In multi-user operation, init's role is to create a process for each
     terminal port on which a user may log in.  To begin such operations, it
     reads the file /etc/ttys and executes a command for each terminal
     specified in the file.  This command will usually be /etc/getty.  getty
     opens and initializes the terminal line, reads the user's name and
     invokes login to log in the user and execute the shell.

     Ultimately the shell will terminate because of an end-of-file either
     typed explicitly or generated as a result of hanging up.  The main path
     of init, which has been waiting for such an event, wakes up and removes
     the appropriate entry from the file utmp, which records current users,
     and makes an entry in /usr/adm/wtmp, which maintains a history of logins
     and logouts.  The wtmp entry is made only if a user logged in
     successfully on the line.  Then the appropriate terminal is reopened and
     getty is reinvoked.

     init catches the hangup signal and interprets it to mean that the file
     /etc/ttys should be read again.  The shell process on each line which
     used to be active in ttys but is no longer there is terminated; a new
     process is created for each added line; lines unchanged in the file are
     undisturbed.  Thus it is possible to drop or add terminal lines without
     rebooting the system by changing the ttys file and sending a hangup
     signal to the init process: use kill -1 1.

     init will terminate multi-user operations and resume single-user mode if
     sent a terminate signal.  If there are processes outstanding which are
     deadlocked (due to hardware or software failure), init will not wait for
     them all to die (which might take forever), but will time out after 30
     seconds and print a warning message.

     init will cease creating new getty's and allow the system to slowly die
     away, if it is sent a terminal stop signal.  A later hangup will resume
     full multi-user operations, or a terminate will initiate a single user
     shell.

     init's role is so critical that if it dies, the system will reboot itself
     automatically.

DIAGNOSTICS
     /etc/getty gettyargs failing, sleeping.

     A process being started to service a line is exiting quickly each time it
     is started.  This is often caused by a ringing or noisy terminal line.
     init will sleep for 30 seconds, then continue trying to start the
     process.

FILES
     /dev/console
     /dev/tty*
     /etc/utmp

     /usr/adm/wtmp
     /etc/ttys
     /etc/rc

SEE ALSO
     login(1), kill(1), sh(1), getty(1m), rc(1m), shutdown(1m)