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35 .\" @(#)init.8 8.3 (Berkeley) 4/18/94
36 .\" $FreeBSD: src/sbin/init/init.8,v 1.22.2.11 2003/05/03 22:19:20 keramida Exp $
37 .\" $DragonFly: src/sbin/init/init.8,v 1.5 2007/07/14 21:48:15 swildner Exp $
44 .Nd process control initialization
56 is the last stage of the boot process.
57 It normally runs the automatic reboot sequence as described in
59 and if this succeeds, begins multi-user operation.
60 If the reboot scripts fail,
62 commences single-user operation by giving
63 the super-user a shell on the console.
66 utility may be passed parameters
67 from the boot program to
68 prevent the system from going multi-user and to instead execute
69 a single-user shell without starting the normal daemons.
70 The system is then quiescent for maintenance work and may
71 later be made to go to multi-user by exiting the
72 single-user shell (with ^D).
78 start up command file in fastboot mode (skipping disk checks).
88 will require that the super-user password be
89 entered before the system will start a single-user shell.
90 The password check is skipped if the
95 The kernel runs with five different levels of security.
96 Any super-user process can raise the security level, but no process
98 The security levels are:
101 Permanently insecure mode \- always run the system in level 0 mode.
102 This is the default initial value.
104 Insecure mode \- immutable and append-only flags may be turned off.
105 All devices may be read or written subject to their permissions.
107 Secure mode \- the system immutable and system append-only flags may not
109 disks for mounted file systems,
113 may not be opened for writing;
116 may not be loaded or unloaded.
118 Highly secure mode \- same as secure mode, plus disks may not be
119 opened for writing (except by
121 whether mounted or not.
122 This level precludes tampering with file systems by unmounting them,
123 but also inhibits running
125 while the system is multi-user.
127 In addition, kernel time changes are restricted to less than or equal to one
128 second. Attempts to change the time by more than this will log the message
129 .Dq Time adjustment clamped to +1 second .
131 Network secure mode \- same as highly secure mode, plus
132 IP packet filter rules (see
136 cannot be changed and
138 configuration cannot be adjusted.
141 If the security level is initially nonzero, then
146 raises the level to 1 before going multi-user for the first time.
147 Since the level cannot be reduced, it will be at least 1 for
148 subsequent operation, even on return to single-user.
149 If a level higher than 1 is desired while running multi-user,
150 it can be set before going multi-user, e.g., by the startup script
156 variable to the required security level.
158 In multi-user operation,
161 processes for the terminal ports found in the file
165 utility reads this file and executes the command found in the second field,
166 unless the first field refers to a device in
168 which is not configured.
169 The first field is supplied as the final argument to the command.
170 This command is usually
173 opens and initializes the tty line
180 program, when a valid user logs in,
181 executes a shell for that user. When this shell
182 dies, either because the user logged out
183 or an abnormal termination occurred (a signal),
186 utility wakes up, deletes the user
189 file of current users and records the logout in the
201 utility can also be used to keep arbitrary daemons running,
202 automatically restarting them if they die.
203 In this case, the first field in the
205 file must not reference the path to a configured device node
206 and will be passed to the daemon
207 as the final argument on its command line.
208 This is similar to the facility offered in the
212 Line status (on, off, secure, getty, or window information)
213 may be changed in the
215 file without a reboot by sending the signal
220 .Dq Li "kill -HUP 1" .
221 On receipt of this signal,
226 When a line is turned off in
229 will send a SIGHUP signal to the controlling process
230 for the session associated with the line.
231 For any lines that were previously turned off in the
235 executes the command specified in the second field.
236 If the command or window field for a line is changed,
237 the change takes effect at the end of the current
238 login session (e.g., the next time
240 starts a process on the line).
241 If a line is commented out or deleted from
244 will not do anything at all to that line.
245 However, it will complain that the relationship between lines
248 file and records in the
251 so this practice is not recommended.
255 utility will terminate multi-user operations and resume single-user mode
259 .Dq Li "kill \-TERM 1" .
260 If there are processes outstanding that are deadlocked (because of
261 hardware or software failure),
263 will not wait for them all to die (which might take forever), but
264 will time out after 30 seconds and print a warning message.
268 utility will cease creating new processes
269 and allow the system to slowly die away, if it is sent a terminal stop
272 .Dq Li "kill \-TSTP 1" .
273 A later hangup will resume full
274 multi-user operations, or a terminate will start a single-user shell.
282 utility will terminate all possible processes (again, it will not wait
283 for deadlocked processes) and reboot the machine if sent the interrupt
286 .Dq Li "kill \-INT 1".
287 This is useful for shutting the machine down cleanly from inside the kernel
288 or from X when the machine appears to be hung.
292 utility will do the same, except it will halt the machine if sent
293 the user defined signal 1
295 or will halt and turn the power off (if hardware permits) if sent
296 the user defined signal 2
299 When shutting down the machine,
304 This script can be used to cleanly terminate specific programs such
307 (the InterNetNews server).
311 is so critical that if it dies, the system will reboot itself
313 If, at bootstrap time, the
315 process cannot be located, the system will panic with the message
316 .Dq "panic: init died (signal %d, exit %d)" .
318 If run as a user process as shown in the second synopsis line,
322 behavior, i.e. super-user can specify the desired
324 on a command line, and
326 will signal the original
330 .Bl -column Run-level SIGTERM
331 .It Sy "Run-level Signal Action
332 .It Cm 0 Ta Dv SIGUSR2 Ta "Halt and turn the power off"
333 .It Cm 1 Ta Dv SIGTERM Ta "Go to single-user mode"
334 .It Cm 6 Ta Dv SIGINT Ta "Reboot the machine"
335 .It Cm c Ta Dv SIGTSTP Ta "Block further logins"
336 .It Cm q Ta Dv SIGHUP Ta Rescan the
341 .Bl -tag -width /etc/rc.shutdown -compact
343 system console device
345 terminal ports found in
348 record of current users on the system
350 record of all logins and logouts
352 the terminal initialization information file
354 system startup commands
355 .It Pa /etc/rc.shutdown
356 system shutdown commands
360 .It "getty repeating too quickly on port %s, sleeping."
361 A process being started to service a line is exiting quickly
362 each time it is started.
363 This is often caused by a ringing or noisy terminal line.
365 Init will sleep for 30 seconds,
366 then continue trying to start the process.
368 .It "some processes would not die; ps axl advised."
370 is hung and could not be killed when the system was shutting down.
371 This condition is usually caused by a process
372 that is stuck in a device driver because of
373 a persistent device error condition.
399 behave as though they have security level \-1.
401 Setting the security level above 1 too early in the boot sequence can
404 from repairing inconsistent file systems. The
405 preferred location to set the security level is at the end of
407 after all multi-user startup actions are complete.