]>
Commit | Line | Data |
---|---|---|
fea681da MK |
1 | .\" Copyright (c) 1998 Andries Brouwer (aeb@cwi.nl), 24 September 1998 |
2 | .\" | |
93015253 | 3 | .\" %%%LICENSE_START(VERBATIM) |
fea681da MK |
4 | .\" Permission is granted to make and distribute verbatim copies of this |
5 | .\" manual provided the copyright notice and this permission notice are | |
6 | .\" preserved on all copies. | |
7 | .\" | |
8 | .\" Permission is granted to copy and distribute modified versions of this | |
9 | .\" manual under the conditions for verbatim copying, provided that the | |
10 | .\" entire resulting derived work is distributed under the terms of a | |
11 | .\" permission notice identical to this one. | |
c13182ef | 12 | .\" |
fea681da MK |
13 | .\" Since the Linux kernel and libraries are constantly changing, this |
14 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
15 | .\" responsibility for errors or omissions, or for damages resulting from | |
16 | .\" the use of the information contained herein. The author(s) may not | |
17 | .\" have taken the same level of care in the production of this manual, | |
18 | .\" which is licensed free of charge, as they might when working | |
19 | .\" professionally. | |
c13182ef | 20 | .\" |
fea681da MK |
21 | .\" Formatted or processed versions of this manual, if unaccompanied by |
22 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 23 | .\" %%%LICENSE_END |
7822805d | 24 | .\" |
c11b1abf | 25 | .\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com> |
fea681da MK |
26 | .\" Added notes on capability requirements |
27 | .\" | |
4cead6db | 28 | .TH REBOOT 2 2013-12-28 "Linux" "Linux Programmer's Manual" |
fea681da MK |
29 | .SH NAME |
30 | reboot \- reboot or enable/disable Ctrl-Alt-Del | |
31 | .SH SYNOPSIS | |
e81aee2d MK |
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: */ | |
fea681da MK |
36 | .sp |
37 | .B #include <unistd.h> | |
38 | .br | |
39 | .B #include <linux/reboot.h> | |
40 | .sp | |
350d584d | 41 | .BI "int reboot(int " magic ", int " magic2 ", int " cmd ", void *" arg ); |
fea681da | 42 | .sp |
e81aee2d MK |
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: */ | |
fea681da MK |
46 | .sp |
47 | .B #include <unistd.h> | |
48 | .br | |
49 | .B #include <sys/reboot.h> | |
50 | .sp | |
350d584d | 51 | .BI "int reboot(int " cmd ); |
fea681da | 52 | .SH DESCRIPTION |
c13182ef | 53 | The |
e511ffb6 | 54 | .BR reboot () |
fea681da MK |
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 | |
58 | .BR loadkeys (1)). | |
59 | .PP | |
682edefb MK |
60 | This system call will fail (with |
61 | .BR EINVAL ) | |
62 | unless | |
fea681da | 63 | .I magic |
682edefb | 64 | equals |
0daa9e92 | 65 | .B LINUX_REBOOT_MAGIC1 |
682edefb | 66 | (that is, 0xfee1dead) and |
fea681da | 67 | .I magic2 |
682edefb | 68 | equals |
0daa9e92 | 69 | .B LINUX_REBOOT_MAGIC2 |
682edefb MK |
70 | (that is, 672274793). |
71 | However, since 2.1.17 also | |
0daa9e92 | 72 | .B LINUX_REBOOT_MAGIC2A |
682edefb MK |
73 | (that is, 85072278) |
74 | and since 2.1.97 also | |
0daa9e92 | 75 | .B LINUX_REBOOT_MAGIC2B |
682edefb MK |
76 | (that is, 369367448) |
77 | and since 2.5.71 also | |
0daa9e92 | 78 | .B LINUX_REBOOT_MAGIC2C |
682edefb | 79 | (that is, 537993216) |
fea681da MK |
80 | are permitted as value for |
81 | .IR magic2 . | |
82 | (The hexadecimal values of these constants are meaningful.) | |
83 | The | |
350d584d | 84 | .I cmd |
fea681da MK |
85 | argument can have the following values: |
86 | .TP | |
939fd8db | 87 | .B LINUX_REBOOT_CMD_CAD_OFF |
4cead6db MK |
88 | .RB ( RB_DISABLE_CAD , |
89 | 0). | |
939fd8db MK |
90 | CAD is disabled. |
91 | This means that the CAD keystroke will cause a | |
92 | .B SIGINT | |
93 | signal to be | |
94 | sent to init (process 1), whereupon this process may decide upon a | |
95 | proper action (maybe: kill all processes, sync, reboot). | |
96 | .TP | |
97 | .B LINUX_REBOOT_CMD_CAD_ON | |
4cead6db MK |
98 | .RB ( RB_ENABLE_CAD , |
99 | 0x89abcdef). | |
939fd8db MK |
100 | CAD is enabled. |
101 | This means that the CAD keystroke will immediately cause | |
102 | the action associated with | |
103 | .BR LINUX_REBOOT_CMD_RESTART . | |
fea681da MK |
104 | .TP |
105 | .B LINUX_REBOOT_CMD_HALT | |
4cead6db MK |
106 | .RB ( RB_HALT_SYSTEM , |
107 | 0xcdef0123; since Linux 1.1.76). | |
2d986c92 | 108 | The message "System halted." is printed, and the system is halted. |
fea681da MK |
109 | Control is given to the ROM monitor, if there is one. |
110 | If not preceded by a | |
111 | .BR sync (2), | |
112 | data will be lost. | |
113 | .TP | |
d1d5d51c | 114 | .BR LINUX_REBOOT_CMD_KEXEC |
4cead6db | 115 | .RB ( RB_KEXEC , |
fd00f12c | 116 | 0x45584543, since Linux 2.6.13). |
939fd8db MK |
117 | Execute a kernel that has been loaded earlier with |
118 | .BR kexec_load (2). | |
33a0ccb2 | 119 | This option is available only if the kernel was configured with |
939fd8db MK |
120 | .BR CONFIG_KEXEC . |
121 | .TP | |
fea681da | 122 | .B LINUX_REBOOT_CMD_POWER_OFF |
4cead6db MK |
123 | .RB ( RB_POWER_OFF , |
124 | 0x4321fedc; since Linux 2.1.30). | |
2d986c92 | 125 | The message "Power down." is printed, the system is stopped, |
fea681da MK |
126 | and all power is removed from the system, if possible. |
127 | If not preceded by a | |
128 | .BR sync (2), | |
129 | data will be lost. | |
130 | .TP | |
939fd8db | 131 | .B LINUX_REBOOT_CMD_RESTART |
4cead6db MK |
132 | .RB ( RB_AUTOBOOT , |
133 | 0x1234567). | |
939fd8db MK |
134 | The message "Restarting system." is printed, and a default |
135 | restart is performed immediately. | |
136 | If not preceded by a | |
137 | .BR sync (2), | |
138 | data will be lost. | |
139 | .TP | |
fea681da | 140 | .B LINUX_REBOOT_CMD_RESTART2 |
0b23bb07 | 141 | (0xa1b2c3d4; since Linux 2.1.30). |
9708eb37 | 142 | The message "Restarting system with command \(aq%s\(aq" is printed, |
fea681da MK |
143 | and a restart (using the command string given in |
144 | .IR arg ) | |
145 | is performed immediately. | |
146 | If not preceded by a | |
147 | .BR sync (2), | |
148 | data will be lost. | |
2d37a960 EDB |
149 | .TP |
150 | .BR LINUX_REBOOT_CMD_SW_SUSPEND | |
4cead6db MK |
151 | .RB ( RB_SW_SUSPEND , |
152 | 0xd000fce1; since Linux 2.5.18). | |
2d37a960 EDB |
153 | The system is suspended (hibernated) to disk. |
154 | This option is available only if the kernel was configured with | |
155 | .BR CONFIG_HIBERNATION . | |
fea681da | 156 | .LP |
350d584d MK |
157 | Only the superuser may call |
158 | .BR reboot (). | |
fea681da MK |
159 | .LP |
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 | |
84c517a4 | 163 | determined by kernel command-line arguments ("reboot=...") to be |
fea681da | 164 | either warm or cold, and either hard or through the BIOS. |
47297adb | 165 | .SH RETURN VALUE |
350d584d MK |
166 | For the values of |
167 | .I cmd | |
168 | that stop or restart the system, | |
169 | a successful call to | |
170 | .BR reboot () | |
171 | does not return. | |
172 | For the other | |
173 | .I cmd | |
174 | values, zero is returned on success. | |
175 | In all cases, \-1 is returned on failure, and | |
fea681da MK |
176 | .I errno |
177 | is set appropriately. | |
178 | .SH ERRORS | |
179 | .TP | |
180 | .B EFAULT | |
7fac88a9 | 181 | Problem with getting user-space data under |
682edefb | 182 | .BR LINUX_REBOOT_CMD_RESTART2 . |
fea681da MK |
183 | .TP |
184 | .B EINVAL | |
350d584d | 185 | Bad magic numbers or \fIcmd\fP. |
fea681da MK |
186 | .TP |
187 | .B EPERM | |
c13182ef | 188 | The calling process has insufficient privilege to call |
e511ffb6 | 189 | .BR reboot (); |
fea681da MK |
190 | the |
191 | .B CAP_SYS_BOOT | |
192 | capability is required. | |
47297adb | 193 | .SH CONFORMING TO |
e511ffb6 | 194 | .BR reboot () |
8382f16d | 195 | is Linux-specific, |
97c1eac8 | 196 | and should not be used in programs intended to be portable. |
47297adb | 197 | .SH SEE ALSO |
fea681da MK |
198 | .BR sync (2), |
199 | .BR bootparam (7), | |
200 | .BR capabilities (7), | |
201 | .BR ctrlaltdel (8), | |
202 | .BR halt (8), | |
203 | .BR reboot (8) |