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  man pages->Tru64 Unix man pages -> init (8)              



NAME    [Toc]    [Back]

       init - Process control initialization

SYNOPSIS    [Toc]    [Back]

       /sbin/init  [0123456789MmQqSs]

OPTIONS    [Toc]    [Back]

       Shuts down and halts the system.  Changes the run level to
       a  multiuser  state  with  local  processes  and  daemons.
       Changes  the  run  level  to a multiuser state with remote
       processes and daemons.  Changes run level to  that  specified
 by the number option in the /etc/inittab file.  If no
       such entry exists, no action is taken and  no  message  is
       output.   Moves control to the console device and halts to
       single-user mode.  Forces init to reexamine the entries in
       the  inittab  file and terminates any live processes which
       have  had  their  configuration   entries   removed   from
       /etc/inittab.   Users should be aware that when a getty(8)
       line has been removed from/etc/inittab, and a login  shell
       is  active  on  the terminal line that was formerly designated
 in inittab as a getty entry, the login shell will be
       killed.  Changes the run level to a single user state with
       only the essential kernel services.

DESCRIPTION    [Toc]    [Back]

       The init program initializes the system  by  creating  and
       controlling  processes.  The processes run by init at each
       run level are defined in the inittab file. The  init  program
  reads and processes the entries in the inittab file.

       The init program considers the system to be in a run level
       at  any given time; each run level has a specific group of
       processes that run at that level. The init  program  operates
  in  one  of eleven run levels: 0-9 and Ss. Of these,
       only -0, -s, -2, and -3 are configured in the inittab file
       by default.

       The run level changes when a privileged user invokes init.
       The new init sends appropriate  signals  to  the  original
       init that tell it which run level to change to.

       Running the init program is the last step in the boot process
 after the root file system is mounted.  The init program
  scans  the  inittab file and looks for an entry with
       the initdefault keyword.  If the entry is there, init uses
       the  run  level specified in that entry as the initial run
       level to enter. If the entry is not found in the<filename>
       inittab</filename>  file  or  if the inittab file does not
       exist, init requests that the user enter a run level  from
       the  system  console, /dev/console. If the user enters the
       letter s, init enters single user state, assigns the  virtual
  console terminal to the user's terminal and opens it
       for reading and writing.  The su command  is  invoked  and
       the  system  displays a message on the console stating the
       location of the virtual console.

       To change the run level, the user specifies either the  0,
       2, 3, or s option.

       For  the  first post-boot execution of init to a run level
       other than single user,  it searches the inittab file  for
       entries  at  the new run level that have the boot or bootwait
 keywords.  If the run level that is specified matches
       the  entry,  the init program acts on these entries before
       processing other entries in the inittab file.  Any special
       initialization  of the system, such as checking and mounting
 file systems, takes place before users are allowed  on
       the  system.  The init program then scans the inittab file
       to find all entries that are to be handled for that level.

       Before  starting  a  new process, init reads each entry in
       the inittab file,  and  for  each  entry  that  should  be
       respawned, init forks a child process.  After spawning all
       required processes, init waits for one of  its  descendant
       processes  to  stop, a power-fail signal, or a signal that
       it should change the run level. If one  of  the  preceding
       three conditions occurs, init reexamines the inittab file.
       You can add new entries to the inittab file, but init does
       not  reexamine  the  file  until one of the three previous
       conditions actually occurs. To immediately  reexamine  the
       inittab file, invoke the init program with the q option.

FILES    [Toc]    [Back]

       Specifies the command path Specifies the init command control
 file Specifies the permanent login accounting file

SEE ALSO    [Toc]    [Back]

       Commands: getty(8), rc0(8), rc2(8), rc3(8), shutdown(8)

       Functions: kill(2), reboot(2)

       Files: inittab(4)

[ Back ]
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