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33 .Nd reboot system or halt processor
40 .Fn reboot "int howto"
46 Only the super-user may reboot a machine on demand.
47 However, a reboot is invoked
48 automatically in the event of unrecoverable system failures.
53 is a mask of options; the system call interface allows the following
54 options, defined in the include file
57 to the new kernel or the new bootstrap and init programs.
58 .Bl -tag -width RB_POWERCYCLE
60 The default, causing the system to reboot in its usual fashion.
62 Normally the system only prompts the user if the loader specified root
63 file system has an error.
64 This flag forces it to always prompt the user for the root partition.
66 Use the compiled in root device.
67 Normally, the system uses the device from which it was booted
68 as the root device if possible.
69 (The default behavior is dependent on the ability of the bootstrap program
70 to determine the drive from which it was loaded, which is not possible
73 Dump kernel memory before rebooting; see
77 The processor is simply halted; no reboot takes place.
78 This option should be used with caution.
80 After halting, the shutdown code will do what it can to turn
81 off the power and then turn the power back on.
82 This requires hardware support, usually an auxiliary microprocessor
83 that can sequence the power supply.
86 driver implements this feature.
88 After halting, the shutdown code will do what it can to turn
90 This requires hardware support.
92 Load the symbol table and enable a built-in debugger in the system.
93 This option will have no useful function if the kernel is not configured
95 Several other options have different meaning if combined
96 with this option, although their use may not be possible
102 for more information.
104 Normally, the disks are sync'd (see
106 before the processor is halted or rebooted.
107 This option may be useful if file system changes have been made manually
108 or if the processor is on fire.
110 Instead of rebooting, unmount all filesystems except the one containing
111 currently-running executable, and mount root filesystem using the same
112 mechanism which is used during normal boot, based on
117 Initially mount the root file system read-only.
118 This is currently the default, and this option has been deprecated.
120 Normally, the reboot procedure involves an automatic disk consistency
121 check and then multi-user operations.
123 prevents this, booting the system with a single-user shell
126 is actually interpreted by the
128 program in the newly booted system.
131 When no options are given (i.e.,
133 is used), the system is
136 in the root file system of unit 0
137 of a disk chosen in a processor specific way.
138 An automatic consistency check of the disks is normally performed
142 If successful, this call never returns.
143 Otherwise, a -1 is returned and an error is returned in the global
149 The caller is not the super-user.
161 system call appeared in