On Monday 12 December 2005 14:20, Blaisorblade wrote:
> First, you can say con1=fd:0,fd:1 instead to redirect tty1 to stdin/out,
> however you just need to add an entry in inittab for tty0 along with tty1
> and list tty0 in /etc/*securetty* (path varies) to allow root to login from
> tty0. Don't use /dev/console as that is very different and has problems
> (aka Ctrl-C, Ctrl-Z don't work, for instance).
It's a little more complicated than that. Signals are blocked for PID 1 so
Ctrl-C and Ctrl-Z can't ever work for init=/bin/sh.
Attached is a dumb little program I use to get around this.
Rob
--
Steve Ballmer: Innovation! Inigo Montoya: You keep using that word.
I do not think it means what you think it means.
/* oneit.c, tiny one-process init replacement.
*
* Copyright 2005 by Rob Landley. Released under gpl v2.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/reboot.h>
// The minimum amount of work necessary to get ctrl-c and such to work is:
//
// - Fork a child (PID 1 is special: can't exit, has various signals blocked).
// - Do a setsid() (so we have our own session).
// - In the child, attach stdio to /dev/tty0 (/dev/console is special)
// - Exec the rest of the command line.
//
// PID 1 then reaps zombies until the child process it spawned exits, at which
// point it calls sync() and reboot(). I could stick a kill -1 in there.
int main(int argc, char *argv[])
{
int a;
pid_t pid;
// pid 1 just reaps zombies until it gets its child, then halts the system.
pid=fork();
if(pid) {
while(pid!=wait());
sync();
reboot(LINUX_REBOOT_CMD_HALT);
}
// Redirect stdio to /dev/tty0, with new session ID, so ctrl-c works.
setsid();
for(a=0;a<3;a++) {
close(a);
open("/dev/tty0",O_RDWR);
}
execvp(argv[1],argv+1);
dprintf(2,"oneit: Can't exec %s\n",argv[1]);
}
