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28 .\" @(#)shutdown.8 8.2 (Berkeley) 4/27/95
29 .\" $FreeBSD: src/sbin/shutdown/shutdown.8,v 1.12.2.5 2003/02/23 21:17:43 trhodes Exp $
30 .\"
31 .Dd September 29, 2016
32 .Dt SHUTDOWN 8
33 .Os
34 .Sh NAME
35 .Nm shutdown ,
36 .Nm poweroff
37 .Nd "close down the system at a given time"
38 .Sh SYNOPSIS
39 .Nm
40 .Op Fl
41 .Oo
42 .Fl h | Fl p |
43 .Fl r | Fl k
44 .Oc
45 .Oo
46 .Fl o
47 .Op Fl n
48 .Oc
49 .Ar time
50 .Op Ar warning-message ...
51 .Nm poweroff
52 .Sh DESCRIPTION
53 The
54 .Nm
55 utility provides an automated shutdown procedure for super-users
56 to nicely notify users when the system is shutting down,
57 saving them from system administrators, hackers, and gurus, who
58 would otherwise not bother with such niceties.
59 .Pp
60 The following options are available:
61 .Bl -tag -width indent
62 .It Fl h
63 The system is halted at the specified
64 .Ar time .
65 .It Fl p
66 The system is halted and the power is turned off
67 (hardware support required)
68 at the specified
69 .Ar time .
70 .It Fl r
71 The system is rebooted at the specified
72 .Ar time .
73 .It Fl k
74 Kick everybody off.
75 The
76 .Fl k
77 option
78 does not actually halt the system, but leaves the
79 system multi-user with logins disabled (for all but super-user).
80 .It Fl o
81 If one of the
82 .Fl h ,
83 .Fl p
84 or
85 .Fl r
86 is specified,
87 .Nm
88 will execute
89 .Xr halt 8
90 or
91 .Xr reboot 8
92 instead of sending signal to
93 .Xr init 8 .
94 .It Fl n
95 If the
96 .Fl o
97 is specified, prevent the file system cache from being flushed by passing
98 .Fl n
99 option to
100 .Xr halt 8
101 or
102 .Xr reboot 8 .
103 This option should probably not be used.
104 .It Ar time
105 .Ar Time
106 is the time at which
107 .Nm
108 will bring the system down and
109 may be the word
110 .Ar now
111 (indicating an immediate shutdown) or
112 specify a future time in one of two formats:
113 .Ar +number ,
114 or
115 .Ar yymmddhhmm ,
116 where the year, month, and day may be defaulted
117 to the current system values. The first form brings the system down in
118 .Ar number
119 minutes and the second at the absolute time specified.
120 .It Ar warning-message
121 Any other arguments comprise the warning message that is broadcast
122 to users currently logged into the system.
123 .It Fl
124 If
125 .Sq Fl
126 is supplied as an option, the warning message is read from the standard
127 input.
128 .El
129 .Pp
130 At intervals, becoming more frequent as apocalypse approaches
131 and starting at ten hours before shutdown, warning messages are displayed
132 on the terminals of all users logged in. Five minutes before
133 shutdown, or immediately if shutdown is in less than 5 minutes,
134 logins are disabled by creating
135 .Pa /var/run/nologin
136 and copying the
137 warning message there. If this file exists when a user attempts to
138 log in,
139 .Xr login 1
140 prints its contents and exits. The file is
141 removed just before
142 .Nm
143 exits.
144 .Pp
145 At shutdown time a message is written to the system log, containing the
146 time of shutdown, the person who initiated the shutdown and the reason.
147 Corresponding signal is then sent to
148 .Xr init 8
149 to respectively halt, reboot or bring the system down to single-user state
150 (depending on the above options).
151 The time of the shutdown and the warning message
152 are placed in
153 .Pa /var/run/nologin
154 and should be used to
155 inform the users about when the system will be back up
156 and why it is going down (or anything else).
157 .Pp
158 A scheduled shutdown can be canceled by killing the
159 .Nm
160 process (a
161 .Dv SIGTERM
162 should suffice).
163 The
164 .Pa /var/run/nologin
165 file that
166 .Nm
167 created will be removed automatically.
168 .Pp
169 Calling
170 .Dq Nm poweroff
171 is equivalent to running:
172 .Bd -literal -offset indent
173 shutdown -p now
174 .Ed
175 .Sh FILES
176 .Bl -tag -width /var/run/nologin -compact
177 .It Pa /var/run/nologin
178 tells login not to let anyone log in
179 .El
180 .Sh BACKWARD COMPATIBILITY
181 The hours and minutes in the second time format may be separated by
182 a colon (``:'') for backward compatibility.
183 .Sh SEE ALSO
184 .Xr kill 1 ,
185 .Xr login 1 ,
186 .Xr wall 1 ,
187 .Xr nologin 5 ,
188 .Xr halt 8 ,
189 .Xr init 8 ,
190 .Xr reboot 8
191 .Sh HISTORY
192 A
193 .Nm
194 command was originally written by Ian Johnstone for UNSW's modified
195 .At v6 .
196 It was modified and then incorporated in
197 .Bx 4.1 .