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System Administration Commands                                        init(1M)

       init - process control initialization

       /usr/sbin/init [0123456abcQqSs]

       init is the default primordial user process. (Options given to the ker‐
       nel during boot may result in the invocation of an alternative  primor‐
       dial user process, as described on kernel(1M)). init initiates the core
       components of the  service  management  facility,  svc.configd(1M)  and
       svc.startd(1M),  and  restarts these components if they fail. For back‐
       wards 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 environ‐
       ments, such as LANG or LC_CTYPE. init then looks  in  /etc/inittab  for
       the initdefault entry (see inittab(4)). If the initdefault entry:


           init usually uses the run level specified in that entry as the ini‐
           tial 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 property.

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

       S or s

           init goes to the single-user state. In this state, the system  con‐
           sole  device  (/dev/console)  is opened for reading 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 ter‐
           minated (using an end-of-file), init  only  re-initializes  to  the
           single-user state if /etc/inittab does not exist.


           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 inittab(4)). These entries are performed
       before any other processing of /etc/inittab takes place, providing that
       the  run  level entered matches that of the entry. In this way any spe‐
       cial initialization of the operating system, such as mounting file sys‐
       tems,  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 descendant 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;  however,  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 forcibly 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 permit) before any further processing takes
       place. In this way init can perform various cleanup and recording func‐
       tions 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.

       init  uses pam(3PAM) for session management. The PAM configuration pol‐
       icy,  configured  in  either  /etc/pam.conf  or  per-service  files  in
       /etc/pam.d/,  specifies  the  session  management 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

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

         session required

       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.


           Go into firmware.


           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  restrict  the
           system milestone to svc:/milestone/single-user:default.


           Put  the system in multi-user mode. All multi-user environment ter‐
           minal 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 restrict the
           system milestone to svc:/milestone/multi-user:default.


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

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


           Is available to be defined as an alternative multi-user environment
           configuration. It is not necessary for system operation and is usu‐
           ally not used.


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


           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 initialization and test steps, depend‐
           ing on the specific capabilities of the system.


           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


           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 filesystems 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  restrict  the
           system milestone to svc:/milestone/single-user:default.


           System console device.


           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:


               Always set to localtime. To set the system timezone, an  admin‐
               istrator  must  set  the  timezone/localtime  property in time‐
               zone:default SMF service.


               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
               setting of CMASK


               Character characterization information


               Message translation


               Monetary formatting information


               Numeric formatting information


               Time formatting information


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


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


           Controls process dispatching by init.


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


           init state necessary to recover from failure.


           User access and administration information.


           History of user access and administration information.


           A named pipe used for internal communication.

       See attributes(5) for descriptions of the following attributes:

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

       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)

       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  sys‐
       tem  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 some‐
       one makes a typographical error in the inittab file, or  a  program  is
       removed that is referenced in /etc/inittab.

       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 system will loop by
       going to firmware and rebooting continuously.

       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 initde‐
       fault  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 subsequent transition to run
       level 2, this file is removed.

       init uses /var/run/initpipe, a named pipe, for internal communication.

SunOS 5.11                        10 May 2012                         init(1M)
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