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init

Name
     init - process control initialization

Synopsis
     /usr/sbin/init [0123456abcQqSs]

Description
     init is the default primordial user process. (Options  given
     to the kernel during boot may result in the invocation of an
     alternative  primordial  user  process,  as   described   on
     kernel(1M)).  init initiates the core components of the ser-
     vice    management     facility,     svc.configd(1M)     and
     svc.startd(1M),  and restarts these components if they fail.
     For backwards compatibility, init also starts  and  restarts
     general  processes  according  to  /etc/inittab, as desribed
     below.


     The run levels and system booting descriptions  given  below
     are  provided for compatibility purposes only, and otherwise
     made obsolete by the service management facility, smf(5).

  init Failure
     If init exits for any reason other than system shutdown,  it
     will be restarted with process-ID 1.

  Run Level Defined
     At any given time, the system is in one  of  eight  possible
     run  levels.  A  run level is a software configuration under
     which only a selected group of processes  exists.  Processes
     spawned  by init for each of these run levels are defined in
     /etc/inittab. init can be in one of eight  run  levels,  0-6
     and  S  or  s (S and s are identical). The run level changes
     when a privileged user runs /usr/sbin/init.

  init and System Booting
     When the system is booted, init is invoked and the following
     occurs.   First,   it   reads   the   properties   for   the
     svc:/system/environment:init service. Among these properties
     are  values for locale-related environments, such as LANG or
     LC_CTYPE. init then looks in /etc/inittab  for  the  initde-
     fault entry (see inittab(4)). If the initdefault entry:

     exists
         init usually uses the run level specified in that  entry
         as   the   initial  run  level  to  enter  only  if  the
         options/milestone property has not  been  specified  for
         svc.startd(1M).

     does not exist
         The service management facility,  smf(5),  examines  its
         configuration  specified  in  svc.startd(1M), and enters
         the milestone specified by  the  options/milestone  pro-
         perty.



     The initdefault entry in  /etc/inittab  corresponds  to  the
     following run levels:

     S or s
         init goes to the single-user state. In this  state,  the
         system console device (/dev/console) is opened for read-
         ing and  writing  and  the  command  /usr/sbin/su,  (see
         su(1M)), is invoked. Use init to change the run level of
         the system. Note that if the shell is terminated  (using
         an   end-of-file),   init  only  re-initializes  to  the
         single-user state if /etc/inittab does not exist.


     0-6
         init enters the corresponding run level. Run  levels  0,
         5,  and  6  are  reserved states for shutting the system
         down. Run levels 2, 3, and 4 are available as multi-user
         operating states.



     If this is the first time  since  power  up  that  init  has
     entered a run level other than single-user state, init first
     scans /etc/inittab for boot and bootwait entries (see  init-
     tab(4)).  These  entries are performed before any other pro-
     cessing of /etc/inittab takes place, providing that the  run
     level  entered  matches  that  of the entry. In this way any
     special initialization of  the  operating  system,  such  as
     mounting  file  systems,  can  take  place  before users are
     allowed onto the system. init then  scans  /etc/inittab  and
     executes all other entries that are to be processed for that
     run level.


     To spawn each process in /etc/inittab, init reads each entry
     and  for  each  entry  that  should be respawned, it forks a
     child process. After it has spawned  all  of  the  processes
     specified by /etc/inittab, init waits for one of its descen-
     dant processes to die, a powerfail signal, or a signal  from
     another  init process to change the system's run level. When
     one   of   these   conditions   occurs,   init   re-examines
     /etc/inittab.

  inittab Additions
     New entries can be added to /etc/inittab at any  time;  how-
     ever, init still waits for one of the above three conditions
     to occur before re-examining  /etc/inittab.  To  get  around
     this,  init  Q  or  init  q command wakes init to re-examine
     /etc/inittab immediately.


     When init comes up at boot  time  and  whenever  the  system
     changes  from  the  single-user  state to another run state,
     init sets the ioctl(2) states of the console to those  modes
     saved  in  the file /etc/ioctl.syscon. init writes this file
     whenever the single-user state is entered.

  Run Level Changes
     When a run level change request is made, init or a designate
     sends the warning signal (SIGTERM) to all processes that are
     undefined in the target run level.  A  minimum  interval  of
     five seconds is observed before init or its designate forci-
     bly terminates these processes  by  sending  a  kill  signal
     (SIGKILL).  Additionally,  init  informs svc.startd(1M) that
     the run level is changing. svc.startd(1M) then restricts the
     system   to   the   set  of  services  which  the  milestone
     corresponding to the run-level change depends on.


     When init receives a signal telling it  that  a  process  it
     spawned has died, it records the fact and the reason it died
     in /var/adm/utmpx  and  /var/adm/wtmpx  if  it  exists  (see
     who(1)).  A  history  of  the  processes  spawned is kept in
     /var/adm/wtmpx.


     If init  receives  a  powerfail  signal  (SIGPWR)  it  scans
     /etc/inittab  for  special entries of the type powerfail and
     powerwait. These entries are invoked (if the run levels per-
     mit)  before any further processing takes place. In this way
     init can perform various  cleanup  and  recording  functions
     during the powerdown of the operating system.

  Setting Environment Variables
     You can set default values for  environment  variables,  for
     such items as timezone and character formatting, in the list
     of properties for the svc:/system/environment:init service.

Security
     init uses pam(3PAM) for session management. The  PAM  confi-
     guration  policy, configured in either /etc/pam.conf or per-
     service files in /etc/pam.d/, specifies the session  manage-
     ment  module to be used for init. Here is a partial pam.conf
     file with entries for init using the UNIX session management
     module.

       init   session   required    pam_unix_session.so.1



     The equivalent PAM configuration using /etc/pam.d/ would  be
     the following entry in /etc/pam.d/init:

       session required    pam_unix_session.so.1




     If  there  are  no  entries  for   the   init   service   in
     /etc/pam.conf  and  no /etc/pam.d/init file exists, then the
     entries for the "other" service  in  /etc/pam.conf  will  be
     used.  If there are not any entries in /etc/pam.conf for the
     "other" service, then the entries in  /etc/pam.d/other  will
     be used.

Options
     0
         Go into firmware.


     1
         Put the system in system administrator mode.  All  local
         file  systems are mounted. Only a small set of essential
         kernel processes are left  running.  This  mode  is  for
         administrative tasks such as installing optional utility
         packages. All files are  accessible  and  no  users  are
         logged in on the system.

         This request corresponds to a request for smf(5) to res-
         trict  the  system  milestone  to svc:/milestone/single-
         user:default.


     2
         Put  the  system  in  multi-user  mode.  All  multi-user
         environment  terminal processes and daemons are spawned.
         This state is commonly referred  to  as  the  multi-user
         state.

         This request corresponds to a request for smf(5) to res-
         trict  the  system  milestone  to  svc:/milestone/multi-
         user:default.


     3
         Extend  multi-user  mode  by  making   local   resources
         available over the network.

         This request corresponds to a request for smf(5) to res-
         trict  the  system  milestone  to  svc:/milestone/multi-
         user-server:default.


     4
         Is available to be defined as an alternative  multi-user
         environment  configuration. It is not necessary for sys-
         tem operation and is usually not used.


     5
         Shut the machine down so that it is safe to  remove  the
         power. Have the machine remove power, if possible.


     6
         Stop the  operating  system  and  reboot  to  the  state
         defined by the initdefault entry in /etc/inittab.

         The service svc:/system/boot-config:default  is  enabled
         by  default. When the config/fastreboot_default property
         is set to true, init 6 will bypass certain firmware ini-
         tialization  and  test  steps, depending on the specific
         capabilities of the system.


     a,b,c
         Process only those /etc/inittab entries having the a, b,
         or  c  run level set. These are pseudo-states, which may
         be defined to run certain commands,  but  which  do  not
         cause the current run level to change.


     Q,q
         Re-examine /etc/inittab.


     S, s
         Enter single-user mode. This is the only run level  that
         doesn't  require  the  existence of a properly formatted
         /etc/inittab file. If this file does not exist, then  by
         default, the only legal run level that init can enter is
         the single-user mode.  When  in  single-user  mode,  the
         filesystems  required for basic system operation will be
         mounted. When the system comes down to single-user mode,
         these file systems will remain mounted (even if provided
         by a remote file server), and any other  local  filesys-
         tems  will  also  be left mounted. During the transition
         down to single-user mode, all processes started by  init
         or  init.d scripts that should only be running in multi-
         user mode are killed. In addition, any process that  has
         a  utmpx  entry  will  be  killed.  This  last condition
         insures that all port monitors started by  the  SAC  are
         killed  and all services started by these port monitors,
         including ttymon login services, are killed.

         This request corresponds to a request for smf(5) to res-
         trict  the  system  milestone  to svc:/milestone/single-
         user:default.

Files
     /dev/console
         System console device.


     /etc/default/init
         This file is Obsolete and might be removed in  a  future
         release. Instead of obtaining values from this file, the
         init    process     reads     properties     for     the
         svc:/system/environment:init  service.  To  make changes
         that were formerly made by editing /etc/default/init, an
         administrator  with  the  System Administrator or System
         Configuration rights profile can set  the  corresponding
         properties  of the init service instance and refresh the
         instance.

         This read-only file contains environment  variables  and
         their default values. The variables are:

         TZ
             Always set to localtime. To set the system timezone,
             an  administrator  must  set  the timezone/localtime
             property in timezone:default SMF service.


         CMASK
             The mask (see umask(1))  that  init  uses  and  that
             every process inherits from the init process. If not
             set, init uses the mask it inherits from the kernel.
             Note  that  init always attempts to apply a umask of
             022 before creating a file, regardless of  the  set-
             ting of CMASK

         LC_CTYPE
             Character characterization information


         LC_MESSAGES
             Message translation


         LC_MONETARY
             Monetary formatting information


         LC_NUMERIC
             Numeric formatting information


         LC_TIME
             Time formatting information


         LC_ALL
             If  set,  all  other  LC_*  environmental  variables
             take-on this value.


         LANG
             If LC_ALL is not set, and  any  particular  LC_*  is
             also  not  set,  the  value of LANG is used for that
             particular environmental variable.



     /etc/inittab
         Controls process dispatching by init.


     /etc/ioctl.syscon
         ioctl states of the  console,  as  saved  by  init  when
         single-user state is entered.


     /etc/svc/volatile/init.state
         init state necessary to recover from failure.


     /var/adm/utmpx
         User access and administration information.

     /var/adm/wtmpx
         History of user access and administration information.


     /var/run/initpipe
         A named pipe used for internal communication.

Attributes
     See attributes(5) for descriptions of the  following  attri-
     butes:



     tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i)  ATTRI-
     BUTE TYPEATTRIBUTE VALUE _ Availabilitysystem/core-os

See Also
     login(1), sh(1), stty(1), who(1), kernel(1M),  shutdown(1M),
     su(1M),    svc.configd(1M),    svc.startd(1M),   ttymon(1M),
     ioctl(2), kill(2), ctime(3C),  pam(3PAM),  init.d(4),  inittab(4),
     pam.conf(4),  TIMEZONE(4), utmpx(4), attributes(5),
     pam_unix_session(5), smf(5), termio(7I)

Diagnostics
     If  init  finds  that  it  is  respawning  an   entry   from
     /etc/inittab  more than ten times in two minutes, it assumes
     that there is an error in the command string  in  the  entry
     and  generates  an  error  message on the system console. It
     then refuses to respawn this entry until either five minutes
     has elapsed or it receives a signal from a user-spawned init
     command. This prevents init from eating up system  resources
     when  someone  makes  a  typographical  error in the inittab
     file,  or  a  program  is  removed  that  is  referenced  in
     /etc/inittab.

Notes
     init can be run only by a privileged user.


     The S or s  state  must  not  be  used  indiscriminately  in
     /etc/inittab.  When modifying this file, it is best to avoid
     adding this state to any line other than initdefault.


     If a default state is not specified in the initdefault entry
     in  /etc/inittab, state 6 is entered. Consequently, the sys-
     tem will loop by going to firmware  and  rebooting  continu-
     ously.

     If the utmpx file cannot be created when booting the system,
     the  system  will  boot to state "s" regardless of the state
     specified in the initdefault entry in /etc/inittab. This can
     occur if the /var file system is not accessible.


     When a system transitions down to the  S  or  s  state,  the
     /etc/nologin  file  (see nologin(4)) is created. Upon subse-
     quent transition to run level 2, this file is removed.


     init uses /var/run/initpipe, a named pipe, for internal com-
     munication.
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