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28 .\" @(#)shutdown.8 8.2 (Berkeley) 4/27/95
31 .Dd September 21, 2016
37 .Nd "close down the system at a given time"
50 .Op Ar warning-message ...
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.
60 The following options are available:
61 .Bl -tag -width indent
63 The system is halted at the specified
66 The system is halted and the power is turned off
67 (hardware support required)
71 The system is rebooted at the specified
78 does not actually halt the system, but leaves the
79 system multi-user with logins disabled (for all but super-user).
86 options are specified,
92 instead of sending a signal to
97 option is specified, prevent the file system cache from being flushed by passing
103 This option should probably not be used.
108 will bring the system down and
109 may be the case-insensitive word
111 (indicating an immediate shutdown) or
112 a future time in one of two formats:
116 where the year, month, and day may be defaulted
117 to the current system values.
118 The first form brings the system down in
120 minutes and the second at the absolute time specified.
122 may be specified in units other than minutes by appending the corresponding
130 .It Ar warning-message
131 Any other arguments comprise the warning message that is broadcast
132 to users currently logged into the system.
136 is supplied as an option, the warning message is read from the standard
140 At intervals, becoming more frequent as apocalypse approaches
141 and starting at ten hours before shutdown, warning messages are displayed
142 on the terminals of all users logged in.
144 shutdown, or immediately if shutdown is in less than 5 minutes,
145 logins are disabled by creating
148 warning message there.
149 If this file exists when a user attempts to
152 prints its contents and exits.
158 At shutdown time a message is written to the system log, containing the
159 time of shutdown, the person who initiated the shutdown and the reason.
160 The corresponding signal is then sent to
162 to respectively halt, reboot or bring the system down to single-user state
163 (depending on the above options).
164 The time of the shutdown and the warning message
167 and should be used to
168 inform the users about when the system will be back up
169 and why it is going down (or anything else).
171 A scheduled shutdown can be canceled by killing the
180 created will be removed automatically.
182 When run without options, the
184 utility will place the system into single user mode at the
190 is equivalent to running:
191 .Bd -literal -offset indent
195 .Bl -tag -width /var/run/nologin -compact
196 .It Pa /var/run/nologin
199 not to let anyone log in
202 Reboot the system in 30 minutes and display a warning message on the terminals
203 of all users currently logged in:
205 .Dl # shutdown -r +30 \&"System will reboot\&"
207 The hours and minutes in the second time format may be separated by
208 a colon (``:'') for backward compatibility.
220 command was originally written by Ian Johnstone for UNSW's modified
222 It was modified and then incorporated in