Hello, I need some help. how to reboot linux in C/C++ ?
i have try :

1. system ("shutdown -r"); ==> but my adm didn't give acces

2. reboot(0x123456) ==> use Linux/reboot.h, but it need Root acces


did any one can give me the solution

the 2. should be reboot(0x1234567)

From the man 2 reboot page :
It is as this, if you haven't the proper rights to do it,
you can't do it, the programming language has nothing to
do with that

[edit]
sorry I misread the man page,
the 2. should be : reboot(LINUX_REBOOT_CMD_RESTART);

HI,
I don't think that you can reboot the machine with out proper privileges. Do not use the system() call in your code. It will create serious security problems.

why it will create serious security ? i don't undestand.
is there any posible to reboot without root acces ??

For question 2:

Linux is a multi user environment. This means it should allow multiple users to use a machine without the possibility of one user to affect other users. (unless badly configured of course). I assume you wouldn't want someone to reboot you machine while you are reading this. . So unless you have root access you can't reboot it.

If you do have root access and want to reboot it as a normal user (perhaps because you are the only user of the machine), you can configure it in someway but I'm sure it depends on the distribution. For my distribution it works ro run reboot, but I don't remember if it's a configuration that I have made, or it is the default.

When I restart programatically using an my GUI then it get started automatically next time when I start the pc . What to do with this ? I don't want my prog to start automatically next time .

actualy i want to make auto timer shutdown for linux, but i didn't have root acces. The target just local mechine.
is there any way to do it ?

Unless root gives you permission to reboot, lets say by adding something like this:
in the /etc/sudoers file, you cannot reboot the machine.

Running a cron service with root permission

HI all,
Create a C code with reboot(0x123456) to reboot the machine. Compile the program. Make the owner of the program as root and give suid permission to it. Now using this executable an ordinary user can reboot the machine.

is there any X Windows library or QT library to do it ?
so i can use it, becuse so far i have try in c, and newbie in QT.

Hi,
All the libraries are using the int reboot(int magic, int magic2, int flag, void *arg) system call for rebooting the system. See man 2 reboot for more details. This system call needs super user permission. Normally in Linux systems users are not allowed to reboot or turn off the systems because it is a multi-user system. So I don't think that there will be any other functions to reboot the machine with out privileged permission.
You can use the ordinary reboot(int) in Qt. There is no problem in that. But do not make large GUI programs SUID. It will create serious problems. SUID programs are so dangerous.

How about using asm to shut down the mechine ?
can it be shut down normaly or it can be make serious problem ?

You can use ASM, C, C++ anything you want. But the user issuing the reboot command should be privileged. To understand the "serious problems” with system() call and SUID programs I have a sample code for you. Just try this.

main()
{
system("/bin/bash");
}

Compile this code as root. Change the permission of the executable to 711. Make the executable SUID and copy it to /bin.
Now login as an ordinary user and execute this program. You will get a shell with root's privilages!

thx, i have try it and it work so far in my mechine, because i did it by root acces.
but the problem if i haven't root acces to did it.
I haven't idea to reboot it with my less acces.