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 2013-12-28 "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 values for
82 (The hexadecimal values of these constants are meaningful.)
85 argument can have the following values:
87 .B LINUX_REBOOT_CMD_CAD_OFF
88 .RB ( RB_DISABLE_CAD ,
91 This means that the CAD keystroke will cause a
94 sent to init (process 1), whereupon this process may decide upon a
95 proper action (maybe: kill all processes, sync, reboot).
97 .B LINUX_REBOOT_CMD_CAD_ON
101 This means that the CAD keystroke will immediately cause
102 the action associated with
103 .BR LINUX_REBOOT_CMD_RESTART .
105 .B LINUX_REBOOT_CMD_HALT
106 .RB ( RB_HALT_SYSTEM ,
107 0xcdef0123; since Linux 1.1.76).
108 The message "System halted." is printed, and the system is halted.
109 Control is given to the ROM monitor, if there is one.
114 .BR LINUX_REBOOT_CMD_KEXEC
116 0x45584543, since Linux 2.6.13).
117 Execute a kernel that has been loaded earlier with
119 This option is available only if the kernel was configured with
122 .B LINUX_REBOOT_CMD_POWER_OFF
124 0x4321fedc; since Linux 2.1.30).
125 The message "Power down." is printed, the system is stopped,
126 and all power is removed from the system, if possible.
131 .B LINUX_REBOOT_CMD_RESTART
134 The message "Restarting system." is printed, and a default
135 restart is performed immediately.
140 .B LINUX_REBOOT_CMD_RESTART2
141 (0xa1b2c3d4; since Linux 2.1.30).
142 The message "Restarting system with command \(aq%s\(aq" is printed,
143 and a restart (using the command string given in
145 is performed immediately.
150 .BR LINUX_REBOOT_CMD_SW_SUSPEND
151 .RB ( RB_SW_SUSPEND ,
152 0xd000fce1; since Linux 2.5.18).
153 The system is suspended (hibernated) to disk.
154 This option is available only if the kernel was configured with
155 .BR CONFIG_HIBERNATION .
157 Only the superuser may call
160 The precise effect of the above actions depends on the architecture.
161 For the i386 architecture, the additional argument does not do
162 anything at present (2.1.122), but the type of reboot can be
163 determined by kernel command-line arguments ("reboot=...") to be
164 either warm or cold, and either hard or through the BIOS.
168 that stop or restart the system,
174 values, zero is returned on success.
175 In all cases, \-1 is returned on failure, and
177 is set appropriately.
181 Problem with getting user-space data under
182 .BR LINUX_REBOOT_CMD_RESTART2 .
185 Bad magic numbers or \fIcmd\fP.
188 The calling process has insufficient privilege to call
192 capability is required.
196 and should not be used in programs intended to be portable.
200 .BR capabilities (7),