1INIT(8) System Manager's Manual INIT(8)
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6 init, rc - process control initialization
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9 /etc/init
10 /etc/rc
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13 Init is invoked as the last step of the boot procedure (see boot(8)).
14 Generally its role is to create a process for each typewriter on which
15 a user may log in.
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17 When init first is executed the console typewriter /dev/console. is
18 opened for reading and writing and the shell is invoked immediately.
19 This feature is used to bring up a single-user system. If the shell
20 terminates, init comes up multi-user and the process described below is
21 started.
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23 When init comes up multiuser, it invokes a shell, with input taken from
24 the file /etc/rc. This command file performs housekeeping like remov‐
25 ing temporary files, mounting file systems, and starting daemons.
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27 Then init reads the file /etc/ttys and forks several times to create a
28 process for each typewriter specified in the file. Each of these pro‐
29 cesses opens the appropriate typewriter for reading and writing. These
30 channels thus receive file descriptors 0, 1 and 2, the standard input,
31 output and error files. Opening the typewriter will usually involve a
32 delay, since the open is not completed until someone is dialed up and
33 carrier established on the channel. Then /etc/getty is called with
34 argument as specified by the last character of the ttys file line.
35 Getty reads the user's name and invokes login(1) to log in the user and
36 execute the shell.
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38 Ultimately the shell will terminate because of an end-of-file either
39 typed explicitly or generated as a result of hanging up. The main path
40 of init, which has been waiting for such an event, wakes up and removes
41 the appropriate entry from the file utmp, which records current users,
42 and makes an entry in /usr/adm/wtmp, which maintains a history of
43 logins and logouts. Then the appropriate typewriter is reopened and
44 getty is reinvoked.
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46 Init catches the hangup signal SIGHUP and interprets it to mean that
47 the system should be brought from multi user to single user. Use `kill
48 -1 1' to send the hangup signal.
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51 /dev/tty?, /etc/utmp, /usr/adm/wtmp, /etc/ttys, /etc/rc
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54 login(1), kill(1), sh(1), ttys(5), getty(8)
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58 INIT(8)