Very Computer

by **Michel** » Wed, 16 Dec 1998 04:00:00

Hi there,

I have 2 easy( or at least I hope so) questions for you.

#1: I need to load two drivers and make a program run in batch mode at
boot time,say when everything is up and ready for login command.Where do
I put these instructions or what I have to do?

#2: I need,from a C program,to make Linux reboot when something weird is
happening.WHat call I need to do within the program?

Thanks in advance.

Michele

by **Simon Paradi** » Wed, 16 Dec 1998 04:00:00

> Hi there,

> I have 2 easy( or at least I hope so) questions for you.

> #1: I need to load two drivers and make a program run in batch mode at
> boot time,say when everything is up and ready for login command.Where do
> I put these instructions or what I have to do?

Put your stuff in /etc/rc.d/rc.local (assuming you have Slackware, these
files
are probably different under other distributions)

Commands inside this file get executed last just before the system can
accept
logins. For exemple, in this file, I put a command which outputs the
time and date to /etc/motd. That way each time I login, I know when I
last
rebooted my system.

Quote:> #2: I need,from a C program,to make Linux reboot when something weird is
> happening.WHat call I need to do within the program?

system("reboot");

This is not elegant but it might work.

--

/-------------------------+-----------------------------------------\
| Simon Paradis |Try Net Timer Pro, an internet timer for |

| | http://www.microtec.net/~ntpdev |
\-------------------------+-----------------------------------------/

by **Peter Samuels** » Wed, 16 Dec 1998 04:00:00

Quote:> I have 2 easy( or at least I hope so) questions for you.

Yup.

Quote:> #1: I need to load two drivers and make a program run in batch mode
> at boot time,say when everything is up and ready for login
> command.Where do I put these instructions or what I have to do?

Depends on your version of `init'. Which probably depends on your
distribution of Linux. In Debian (which uses sysvinit), for example,
just add the necessary script or a symbolic link to same to /etc/rc2.d/
or whichever runlevel you want this to happen in. For more info read
up on `init'.

Quote:> #2: I need,from a C program,to make Linux reboot when something weird
> is happening.WHat call I need to do within the program?

You could call the reboot syscall directly but the cleanest way to do
this is probably through a watchdog timer. Configure your kernel with
"softdog" support (in the "character devices" section) and read up on
it. Basically this is a file in /dev which your program opens and
periodically writes to. If it closes the file or doesn't write to it
for a certain amount of time, Linux will assume that something has hung
or otherwise gone wrong and will reboot.

--
Peter Samuelson
<sampo.creighton.edu!psamuels>

by **Juergen Hein** » Wed, 16 Dec 1998 04:00:00

>Hi there,

Cheers,
[...]

Quote:>#1: I need to load two drivers and make a program run in batch mode at
>boot time,say when everything is up and ready for login command.Where do
>I put these instructions or what I have to do?

in one of your init scripts, but it depends on you init setup whether
you've something like /etc/rc.local (BSD'ish) or a SYSV init compatible
installation (like here, where there are /etc/rc0.d ... /etc/rc6.d
directories for the different runlevels).

Quote:>#2: I need,from a C program,to make Linux reboot when something weird is
>happening.WHat call I need to do within the program?

It depends on how hard you want to bring the machine down, see the source for
sysvinit for more (esp. since it depends on whether you have libc5 or libc6).

Much better of course is to make a clean shutdown and to fork() / exec()
/sbin/shutdown [args] or /sbin/telinit [runlevel] instead of using reboot()
which is a system call. You're talking straight to the kernel here, no
umount, nothing.

You can even set up a special runlevel for a "panic" shutdown (say, you might
disable all logins *right now*, send a message to your pager and such).

Bye,
Juergen

--
\ Real name : Jrgen Heinzl \ no flames /

\ Phone Private : +44 181-332 0750 \ /

by **Laurent Martell** » Wed, 16 Dec 1998 04:00:00

Michele> Hi there, I have 2 easy( or at least I hope so) questions
Michele> for you.

Michele> #2: I need,from a C program,to make Linux reboot when
Michele> something weird is happening.WHat call I need to do
Michele> within the program?

The simplest is probably to run reboot from you program with
exec. (man exec)

by **Gordon Sco** » Thu, 17 Dec 1998 04:00:00

: #2: I need,from a C program,to make Linux reboot when something weird is
: happening.WHat call I need to do within the program?

I have to suggest you ask yourself if you're really sure you need to do
this. As a rule, Linux is robust enough that things rarely go 'weird',
so the need to self-reboot should may not really exist unless you're
doing something unusual and quite deep within the system.

Most application and peer-machine problems can be dealt with without
the need to reboot. There are various ways to auto-restart applications
if they break.

G.
--
Gordon Scott Opinions expressed are my own.

Linux ............... Because I like to _get_ there today.

by **Pawel Sakows** » Wed, 23 Dec 1998 04:00:00

Quote:>> #2: I need,from a C program,to make Linux reboot when something weird is
>> happening.WHat call I need to do within the program?

>system("reboot");

>This is not elegant but it might work.

I'd rather suggest

system("/sbin/init 6");

--
"We are different"

by **Jorge Delgado Mendoz** » Wed, 30 Dec 1998 04:00:00

> Hi there,

> I have 2 easy( or at least I hope so) questions for you.

> #1: I need to load two drivers and make a program run in batch mode at
> boot time,say when everything is up and ready for login command.Where do
> I put these instructions or what I have to do?

Add it to /etc/rc.d/rc.local

Quote:
> #2: I need,from a C program,to make Linux reboot when something weird is
> happening.WHat call I need to do within the program?

1.- Setuid the program as 'root' (ie. has root privileges)
2.- whenever you want (in the code) issue the system call 'system'

if ( reboot_condition)
system ( "reboot" );

man system, man execve....

Quote:
> Thanks in advance.

> Michele

by **Jürgen Exne** » Tue, 05 Jan 1999 04:00:00

>Hi there,

>I have 2 easy( or at least I hope so) questions for you.

>#1: I need to load two drivers and make a program run in batch mode at
>boot time,say when everything is up and ready for login command.Where do
>I put these instructions or what I have to do?

Check out /etc/rc.d.
/etc/rc.d/local.rc might be a good place for starters

Quote:>#2: I need,from a C program,to make Linux reboot when something weird is
>happening.WHat call I need to do within the program?

What about using e.g. "exec" with "/sbin/shutdown -r now"?
Of course somehow you will need root permissions to reboot.

jue
--
Jrgen Exner; microsoft.com, UID: jurgenex
Sorry for this anti-spam inconvenience

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