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28 .\" @(#)reboot.2 8.1 (Berkeley) 6/4/93
36 .Nd reboot system or halt processor
43 .Fn reboot "int howto"
49 Only the super-user may reboot a machine on demand.
50 However, a reboot is invoked
51 automatically in the event of unrecoverable system failures.
56 is a mask of options; the system call interface allows the following
57 options, defined in the include file
60 to the new kernel or the new bootstrap and init programs.
61 .Bl -tag -width RB_INITNAMEA
63 The default, causing the system to reboot in its usual fashion.
65 Interpreted by the bootstrap program itself, causing it to
66 prompt on the console as to what file should be booted.
67 Normally, the system is booted from the file
68 .Dq Ar xx Ns No (0,0)kernel ,
71 is the default disk name,
72 without prompting for the file name.
74 Use the compiled in root device.
75 Normally, the system uses the device from which it was booted
76 as the root device if possible.
77 (The default behavior is dependent on the ability of the bootstrap program
78 to determine the drive from which it was loaded, which is not possible
81 Dump kernel memory before rebooting; see
85 The processor is simply halted; no reboot takes place.
86 This option should be used with caution.
88 After halting, the shutdown code will do what it can to turn
89 off the power and then turn the power back on.
90 This requires hardware support, usually an auxiliary microprocessor
91 that can sequence the power supply.
94 driver implements this feature.
96 After halting, the shutdown code will do what it can to turn
98 This requires hardware support.
100 An option allowing the specification of an init program (see
104 to be run when the system reboots.
105 This switch is not currently available.
107 Load the symbol table and enable a built-in debugger in the system.
108 This option will have no useful function if the kernel is not configured
110 Several other options have different meaning if combined
111 with this option, although their use may not be possible
117 for more information.
119 Normally, the disks are sync'd (see
121 before the processor is halted or rebooted.
122 This option may be useful if file system changes have been made manually
123 or if the processor is on fire.
125 Instead of rebooting, unmount all filesystems except the one containing
126 currently-running executable, and mount root filesystem using the same
127 mechanism which is used during normal boot, based on
132 Initially mount the root file system read-only.
133 This is currently the default, and this option has been deprecated.
135 Normally, the reboot procedure involves an automatic disk consistency
136 check and then multi-user operations.
138 prevents this, booting the system with a single-user shell
141 is actually interpreted by the
143 program in the newly booted system.
146 When no options are given (i.e.,
148 is used), the system is
151 in the root file system of unit 0
152 of a disk chosen in a processor specific way.
153 An automatic consistency check of the disks is normally performed
157 If successful, this call never returns.
158 Otherwise, a -1 is returned and an error is returned in the global
164 The caller is not the super-user.
175 system call appeared in