shutdown.tproj/shutdown.8

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  32 .\"     @(#)shutdown.8  8.2 (Berkeley) 4/27/95
  33 .\" $FreeBSD: src/sbin/shutdown/shutdown.8,v 1.21 2002/12/23 16:04:50 ru Exp $
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  35 .Dd December 11, 1998
  36 .Dt SHUTDOWN 8
  37 .Os
  38 .Sh NAME
  39 .Nm shutdown
  40 .Nd "close down the system at a given time"
  41 .Sh SYNOPSIS
  42 .Nm shutdown
  43 .Op Fl
  44 .Oo
  45 .Fl h
  46 .Op Fl u
  47 |
  48 .Fl r | Fl s | Fl k
  49 .Oc
  50 .Oo
  51 .Fl o
  52 .Op Fl n
  53 .Oc
  54 .Ar time
  55 .Op Ar warning-message ...
  56 .Sh DESCRIPTION
  57 The
  58 .Nm shutdown
  59 utility provides an automated shutdown procedure for super-users
  60 to nicely notify users when the system is shutting down,
  61 saving them from system administrators, hackers, and gurus, who
  62 would otherwise not bother with such niceties.
  63 .Pp
  64 The following options are available:
  65 .Bl -tag -width indent
  66 .It Fl h
  67 The system is halted at the specified
  68 .Ar time .
  69 .It Fl k
  70 Kick everybody off.
  71 The
  72 .Fl k
  73 option
  74 does not actually halt the system, but leaves the
  75 system multi-user with logins disabled (for all but super-user).
  76 .It Fl n
  77 If the
  78 .Fl o
  79 is specified, prevent the file system cache from being flushed by passing
  80 .Fl n
  81 option to
  82 .Xr halt 8
  83 or
  84 .Xr reboot 8 .
  85 This option should probably not be used.
  86 .It Fl o
  87 If
  88 .Fl h
  89 or
  90 .Fl r
  91 is specified,
  92 .Nm shutdown
  93 will execute
  94 .Xr halt 8
  95 or
  96 .Xr reboot 8
  97 instead of sending a signal to
  98 .Xr launchd 8 .
  99 .It Fl r
 100 The system is rebooted at the specified
 101 .Ar time .
 102 .It Fl s
 103 The system is put to sleep at the specified
 104 .Ar time .
 105 .It Fl u
 106 The system is halted up until the point of removing system power, but waits
 107 before removing power for 5 minutes so that an external UPS
 108 (uninterruptible power supply) can forcibly remove power.
 109 This simulates a dirty shutdown to permit a later automatic power on. OS X uses
 110 this mode automatically with supported UPSs in emergency shutdowns.
 111 .It Ar time
 112 .Ar Time
 113 is the time at which
 114 .Nm shutdown
 115 will bring the system down and
 116 may be the word
 117 .Ar now
 118 (indicating an immediate shutdown) or
 119 specify a future time in one of two formats:
 120 .Ar +number ,
 121 or
 122 .Ar yymmddhhmm ,
 123 where the year, month, and day may be defaulted
 124 to the current system values.  The first form brings the system down in
 125 .Ar number
 126 minutes and the second at the absolute time specified.
 127 .It Ar warning-message
 128 Any other arguments comprise the warning message that is broadcast
 129 to users currently logged into the system.
 130 .It Fl
 131 If
 132 .Sq Fl
 133 is supplied as an option, the warning message is read from the standard
 134 input.
 135 .El
 136 .Pp
 137 At intervals, becoming more frequent as apocalypse approaches
 138 and starting at ten hours before shutdown, warning messages are displayed
 139 on the terminals of all users logged in.
 140 .Pp
 141 At shutdown time a message is written to the system log, containing the
 142 time of shutdown, the person who initiated the shutdown and the reason.
 143 Corresponding signal is then sent to
 144 .Xr launchd 8
 145 to respectively halt, reboot or bring the system down to single-user state
 146 (depending on the above options).
 147 .Pp
 148 A scheduled shutdown can be canceled by killing the
 149 .Nm shutdown
 150 process (a
 151 .Dv SIGTERM
 152 should suffice).
 153 .Sh SIGTERM TO SIGKILL INTERVAL
 154 Upon shutdown, all running processes are sent a SIGTERM followed by a SIGKILL.
 155 The
 156 .Dv SIGKILL
 157 will follow the
 158 .Dv SIGTERM
 159 by an intentionally indeterminate period of time.
 160 Programs are expected to take only enough time to flush all dirty data and exit.
 161 Developers are encouraged to file a bug with the OS vendor, should they encounter an issue with this functionality.
 162 .Sh SEE ALSO
 163 .Xr kill 1 ,
 164 .Xr login 1 ,
 165 .Xr wall 1 ,
 166 .Xr halt 8 ,
 167 .Xr launchd 8 ,
 168 .Xr reboot 8
 169 .Sh BACKWARD COMPATIBILITY
 170 The hours and minutes in the second time format may be separated by
 171 a colon (``:'') for backward compatibility.
 172 .Sh HISTORY
 173 The
 174 .Nm shutdown
 175 utility appeared in
 176 .Bx 4.0 .