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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 $
43 .Nd process control initialization
55 is the last stage of the boot process.
56 It normally runs the automatic reboot sequence as described in
58 and if this succeeds, begins multi-user operation.
59 If the reboot scripts fail,
61 commences single-user operation by giving
62 the super-user a shell on the console.
65 utility may be passed parameters
66 from the boot program to
67 prevent the system from going multi-user and to instead execute
68 a single-user shell without starting the normal daemons.
69 The system is then quiescent for maintenance work and may
70 later be made to go to multi-user by exiting the
71 single-user shell (with ^D).
77 start up command file in fastboot mode (skipping disk checks).
87 will require that the super-user password be
88 entered before the system will start a single-user shell.
89 The password check is skipped if the
94 The kernel runs with five different levels of security.
95 Any super-user process can raise the security level, but no process
97 The security levels are:
100 Permanently insecure mode \- always run the system in level 0 mode.
101 This is the default initial value.
103 Insecure mode \- immutable and append-only flags may be turned off.
104 All devices may be read or written subject to their permissions.
106 Secure mode \- the system immutable and system append-only flags may not
108 disks for mounted file systems,
112 may not be opened for writing;
115 may not be loaded or unloaded.
117 Highly secure mode \- same as secure mode, plus disks may not be
118 opened for writing (except by
120 whether mounted or not.
121 This level precludes tampering with file systems by unmounting them,
122 but also inhibits running
124 while the system is multi-user.
126 In addition, kernel time changes are restricted to less than or equal to one
127 second. Attempts to change the time by more than this will log the message
128 .Dq Time adjustment clamped to +1 second .
130 Network secure mode \- same as highly secure mode, plus
131 IP packet filter rules (see
135 cannot be changed and
137 configuration cannot be adjusted.
140 If the security level is initially nonzero, then
145 raises the level to 1 before going multi-user for the first time.
146 Since the level cannot be reduced, it will be at least 1 for
147 subsequent operation, even on return to single-user.
148 If a level higher than 1 is desired while running multi-user,
149 it can be set before going multi-user, e.g., by the startup script
155 variable to the required security level.
157 In multi-user operation,
160 processes for the terminal ports found in the file
164 utility reads this file and executes the command found in the second field,
165 unless the first field refers to a device in
167 which is not configured.
168 The first field is supplied as the final argument to the command.
169 This command is usually
172 opens and initializes the tty line
179 program, when a valid user logs in,
180 executes a shell for that user. When this shell
181 dies, either because the user logged out
182 or an abnormal termination occurred (a signal),
185 utility wakes up, deletes the user
188 file of current users and records the logout in the
200 utility can also be used to keep arbitrary daemons running,
201 automatically restarting them if they die.
202 In this case, the first field in the
204 file must not reference the path to a configured device node
205 and will be passed to the daemon
206 as the final argument on its command line.
207 This is similar to the facility offered in the
211 Line status (on, off, secure, getty, or window information)
212 may be changed in the
214 file without a reboot by sending the signal
219 .Dq Li "kill -HUP 1" .
220 On receipt of this signal,
225 When a line is turned off in
230 signal to the controlling process 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).
308 If this script does not terminate within 120 seconds,
310 will terminate it. The timeout can be configured via the
313 .Va kern.init_shutdown_timeout .
317 is so critical that if it dies, the system will reboot itself
319 If, at bootstrap time, the
321 process cannot be located, the system will panic with the message
322 .Dq "panic: init died (signal %d, exit %d)" .
324 If run as a user process as shown in the second synopsis line,
328 behavior, i.e. super-user can specify the desired
330 on a command line, and
332 will signal the original
336 .Bl -column Run-level SIGTERM
337 .It Sy "Run-level Signal Action"
338 .It Cm 0 Ta Dv SIGUSR2 Ta "Halt and turn the power off"
339 .It Cm 1 Ta Dv SIGTERM Ta "Go to single-user mode"
340 .It Cm 6 Ta Dv SIGINT Ta "Reboot the machine"
341 .It Cm c Ta Dv SIGTSTP Ta "Block further logins"
342 .It Cm q Ta Dv SIGHUP Ta Rescan the
347 .Bl -tag -width /etc/rc.shutdown -compact
349 system console device
351 terminal ports found in
354 record of current users on the system
356 record of all logins and logouts
358 the terminal initialization information file
360 system startup commands
361 .It Pa /etc/rc.shutdown
362 system shutdown commands
366 .It "getty repeating too quickly on port %s, sleeping."
367 A process being started to service a line is exiting quickly
368 each time it is started.
369 This is often caused by a ringing or noisy terminal line.
371 Init will sleep for 30 seconds,
372 then continue trying to start the process.
374 .It "some processes would not die; ps axl advised."
376 is hung and could not be killed when the system was shutting down.
377 This condition is usually caused by a process
378 that is stuck in a device driver because of
379 a persistent device error condition.
405 behave as though they have security level \-1.
407 Setting the security level above 1 too early in the boot sequence can
410 from repairing inconsistent file systems. The
411 preferred location to set the security level is at the end of
413 after all multi-user startup actions are complete.