Windows PowerShell command on Get-command init

Manual Pages for UNIX Operating System command usage for man init

System Administration Commands init(1M)

NAME

init, telinit - process control initialization

SYNOPSIS

/sbin/init [0123456abcQqSs]

/etc/telinit [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 /sbin/init.

init and System Booting

When the system is booted, init is invoked and the following

occurs. First, it reads /etc/default/init to set environment

variables. This is typically where TZ (time zone) and

locale-related environments such as LANG or LC_CTYPE get

set. (See the FILES section at the end of this page.) init

then looks in /etc/inittab for the initdefault 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

SunOS 5.11 Last change: 24 Feb 2010 1

System Administration Commands init(1M)

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 /sbin/su, (see su(1M)),

is invoked. Use either init or telinit 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.

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

SunOS 5.11 Last change: 24 Feb 2010 2

System Administration Commands init(1M)

specified by /etc/inittab, init waits for one of its descen-

dant processes to die, a powerfail signal, or a signal from

another init or telinit 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.

Environment Variables in /etc/default/init

You can set default values for environment variables, for such items as timezone and character formatting, in

/etc/default/init. See the FILES section, below, for a list

of these variables.

SunOS 5.11 Last change: 24 Feb 2010 3

System Administration Commands init(1M)

telinit

telinit, which is linked to /sbin/init, is used to direct

the actions of init. It takes a one-character argument and

signals init to take the appropriate action.

SECURITY

init uses pam(3PAM) for session management. The PAM confi-

guration policy, listed through /etc/pam.conf, 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 pam_unix_session.so.1

If there are no entries for the init service, then the

entries for the "other" service 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.

SunOS 5.11 Last change: 24 Feb 2010 4

System Administration Commands init(1M)

Extend multi-user mode by making local resources avail-

able 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.

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

SunOS 5.11 Last change: 24 Feb 2010 5

System Administration Commands init(1M)

/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

Contains environment variables and their default values. For example, for the timezone variable, TZ, you might

specify TZ=US/Pacific. The variables are: TZ Either specifies the timezone information (see ctime(3C)) or the name of a timezone information file /usr/share/lib/zoneinfo. Refer to the TIMEZONE(4) man page before changing this setting. 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

SunOS 5.11 Last change: 24 Feb 2010 6

System Administration Commands init(1M)

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

SunOS 5.11 Last change: 24 Feb 2010 7

System Administration Commands init(1M)

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:

____________________________________________________________

| ATTRIBUTE TYPE | ATTRIBUTE VALUE |

|_____________________________|_____________________________|

| Availability | SUNWcs |

|_____________________________|_____________________________|

ioctl(2), kill(2), ctime(3C), pam(3PAM), init.d(4), init-

tab(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

or telinit 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

SunOS 5.11 Last change: 24 Feb 2010 8

System Administration Commands init(1M)

init and telinit 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.

The pam_unix(5) module is no longer supported. Similar func-

tionality is provided by pam_unix_session(5).

SunOS 5.11 Last change: 24 Feb 2010 9