1 .\" Copyright (c) 1998 Andries Brouwer (aeb@cwi.nl), 24 September 1998
3 .\" %%%LICENSE_START(VERBATIM)
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25 .\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
26 .\" Added notes on capability requirements
28 .TH REBOOT 2 2010-10-31 "Linux" "Linux Programmer's Manual"
30 reboot \- reboot or enable/disable Ctrl-Alt-Del
32 /* For libc4 and libc5 the library call and the system call
33 are identical, and since kernel version 2.1.30 there are
34 symbolic names LINUX_REBOOT_* for the constants and a
35 fourth argument to the call: */
37 .B #include <unistd.h>
39 .B #include <linux/reboot.h>
41 .BI "int reboot(int " magic ", int " magic2 ", int " cmd ", void *" arg );
43 /* Under glibc some of the constants involved have gotten
44 symbolic names RB_*, and the library call is a 1-argument
45 wrapper around the 3-argument system call: */
47 .B #include <unistd.h>
49 .B #include <sys/reboot.h>
51 .BI "int reboot(int " cmd );
55 call reboots the system, or enables/disables the reboot keystroke
56 (abbreviated CAD, since the default is Ctrl-Alt-Delete;
57 it can be changed using
60 This system call will fail (with
65 .B LINUX_REBOOT_MAGIC1
66 (that is, 0xfee1dead) and
69 .B LINUX_REBOOT_MAGIC2
71 However, since 2.1.17 also
72 .B LINUX_REBOOT_MAGIC2A
75 .B LINUX_REBOOT_MAGIC2B
78 .B LINUX_REBOOT_MAGIC2C
80 are permitted as value for
82 (The hexadecimal values of these constants are meaningful.)
85 argument can have the following values:
87 .B LINUX_REBOOT_CMD_CAD_OFF
90 This means that the CAD keystroke will cause a
93 sent to init (process 1), whereupon this process may decide upon a
94 proper action (maybe: kill all processes, sync, reboot).
96 .B LINUX_REBOOT_CMD_CAD_ON
97 (RB_ENABLE_CAD, 0x89abcdef).
99 This means that the CAD keystroke will immediately cause
100 the action associated with
101 .BR LINUX_REBOOT_CMD_RESTART .
103 .B LINUX_REBOOT_CMD_HALT
104 (RB_HALT_SYSTEM, 0xcdef0123; since 1.1.76).
105 The message "System halted." is printed, and the system is halted.
106 Control is given to the ROM monitor, if there is one.
111 .BR LINUX_REBOOT_CMD_KEXEC " (since Linux 2.6.13)"
112 Execute a kernel that has been loaded earlier with
114 This option is only available if the kernel was configured with
117 .B LINUX_REBOOT_CMD_POWER_OFF
118 (0x4321fedc; since 2.1.30).
119 The message "Power down." is printed, the system is stopped,
120 and all power is removed from the system, if possible.
125 .B LINUX_REBOOT_CMD_RESTART
126 (RB_AUTOBOOT, 0x1234567).
127 The message "Restarting system." is printed, and a default
128 restart is performed immediately.
133 .B LINUX_REBOOT_CMD_RESTART2
134 (0xa1b2c3d4; since 2.1.30).
135 The message "Restarting system with command \(aq%s\(aq" is printed,
136 and a restart (using the command string given in
138 is performed immediately.
143 Only the superuser may call
146 The precise effect of the above actions depends on the architecture.
147 For the i386 architecture, the additional argument does not do
148 anything at present (2.1.122), but the type of reboot can be
149 determined by kernel command-line arguments ("reboot=...") to be
150 either warm or cold, and either hard or through the BIOS.
154 that stop or restart the system,
160 values, zero is returned on success.
161 In all cases, \-1 is returned on failure, and
163 is set appropriately.
167 Problem with getting user-space data under
168 .BR LINUX_REBOOT_CMD_RESTART2 .
171 Bad magic numbers or \fIcmd\fP.
174 The calling process has insufficient privilege to call
178 capability is required.
182 and should not be used in programs intended to be portable.
186 .BR capabilities (7),