change braodcast message at shutdown

MikTheUser · 07-22-2004, 06:56 PM

hi folks,

nothing serious, I've just been wondering if I could possibly change the "Bradcast message from root (tty1) ..." - I grep-ed it out of /sbin/shutdown, but since that's a binary file, I won't meddle with it.
Any hints?

TIA,
Mik

frob23 · 07-22-2004, 07:03 PM

What do you want it to say?

MikTheUser · 07-23-2004, 03:58 AM

if there's a choice to make, I'd go with "Braodcast message from God (tty0): the Universe is going down for shutdown NOW!"

well, seriously, the trouble with that would be that I'd have t remove two %s-placeholders (the username and tty-indicator) from the message in the binary code - which would lead to programming errors. So... would I have to re-compile it?

frob23 · 07-23-2004, 08:02 AM

Yes, you would have to recompile it. Which is not a serious challenge considering what you want to do. I'll go see if I can find the shutdown source for slackware myself and if I can give you some pointers.

In the meantime, have you tried adding a message to the command?

shutdown -h now "All you guys are going to pay!"

Or something like that... it might meet your needs, although I am not certain it wouldn't print both.

frob23 · 07-23-2004, 08:34 AM

Oh, it looks like you are going to have to change the default behavior of wall... which would be a bad thing. But that is the program that is adding the information you want to change (root->God). You can create an account named God, su into that, and then run shutdown and it might change the name.

For your other change, edit shutdown.c (it is in the sysvinit-2.84.tar.gz file).

Code:

/*
 * Tell everyone the system is going down in 'mins' minutes.
 */
void warn(mins)
int mins;
{
  char buf[MESSAGELEN + sizeof(newstate)];
  int len;

  strncpy(buf, message, sizeof(buf));
  buf[sizeof(buf) - 1] = 0;
  len = strlen(buf);

  if (mins == 0)
        snprintf(buf + len, sizeof(buf) - len,
                "\rThe system is going down %s NOW!\r\n",
                newstate);
  else
        snprintf(buf + len, sizeof(buf) - len,
                "\rThe system is going DOWN %s in %d minute%s!\r\n",
                        newstate, mins, mins == 1 ? "" : "s");
  wall(buf, 1, 0);
}

You need to change system to Universe in both places where it occures. There are other messages where it still says system and you might want to change them also to it reflects the word universe. Rebuild the program, install it with the correct permissions and you are all set.

EDIT: The other program you would change would be dowall.c -- you could do it the easy way, and break its functionality by hardcoding strings, or you could perform a test and if you are root change the string to God. I leave that up as an exercise to you.

Hint: user = pwd ? pwd->pw_name : (uid == 0 ? "root" : uidbuf);
Look for that line. And, YOU MUST REBUILD ALL PROGRAMS THAT DEPEND ON THIS IF YOU CHANGE IT. Just rebuild everything in the directory to be safe.

MikTheUser · 07-24-2004, 01:28 PM

Hi all!

Thanks for your hints! In the end, I settled with echo-ing a Latin bible quote right before powerdown, so I won't have to recompile everything - but I might just take a look at that shutdown code to play around a little - nothing wild tho

Thanks again, Mik

Izra · 11-20-2013, 01:07 AM

I want to change the reboot/shutdown ..message..

Broadcast message from root@Server197
(/dev/pts/0) at 10:49 ...

The system is going down for reboot NOW!

this messages...