Re: Switching between foreground and background

Re: Switching between foreground and background

[John T. Williams]

I have to admit that I don't know why, but every resource I've ever read
about causing programs to gain daemon behavior has involved forking 2 times
and then starting the program code.  If anyone here does know why, I'd would
be happy to hear it.



----- Original Message ----- 
From: "Raghuveer" <rvk@gsecone.com>
To: "John T. Williams" <jtwilliams@vt.edu>
Cc: "Silambu Chelvan" <silambu_mdu@yahoo.com>;
<linux-newbie@vger.kernel.org>
Sent: Tuesday, September 23, 2003 7:01 AM
Subject: Re: Switching between foreground and background


> John T. Williams wrote:
>
> >I think part of the problem here might be conceptual.
> >
> >If I understand what you want, you'd like, on a signal, for your program
to
> >go into the background (still running but no longer blocking the terminal
> >input/output). On another signal you would like the program to come back
to
> >the foreground.
> >
> >If this is the case, the problem you're facing is that the program being
in
> >the foreground and the background is actually part of the shell, not a
> >property of the program running.  Most Shells provide a way to switch
> >programs from the foreground to the background and back.
> >BASH for example I could type
> >
> >$>./myprogram
> >(cntr + Z) //suspends the current program and prings the prompt back
> >$>bg  (runs the program in the background)
> >
> >The only way that I know of to force a program to run in the background
in
> >the code is to make it a daemon which is done by forking twice
> >
> >int main(  ) {
> >   if(fork()==0)  {
> >            if( fork() == 0 )  {
> >                    program code starts here
> >             }
> >            exit(0);
> >    }
> >    exit(0);
> >}
> >
> >
> I don't feel it's required to fork() twice for making it a daemon, once
> is enough. Ya, but should use setpgrp() or setpid() and close stdin, out
> and err after the fork and go to infinite loop.
>
> -Raghu
>
> >
> >----- Original Message ----- 
> >From: "Silambu Chelvan" <silambu_mdu@yahoo.com>
> >To: <linux-newbie@vger.kernel.org>
> >Sent: Monday, September 22, 2003 6:48 AM
> >Subject: Switching between foreground and background
> >
> >
> >
> >
> >>Hi all,
> >>
> >>I have written some program with signal handler. Is
> >>this possible, if
> >>one of the signals registered with my program is
> >>raised, my program
> >>should goto background and should come to foreground
> >>when some other of the
> >>registered signal is raised. how to do it?
> >>
> >>Any function available to switch a process between
> >>foreground and
> >>background at runtime?
> >>
> >>with regards,
> >>M. SilambuChelvan
> >>
> >>
> >>__________________________________
> >>Do you Yahoo!?
> >>Yahoo! SiteBuilder - Free, easy-to-use web site design software
> >>http://sitebuilder.yahoo.com
> >>-
> >>To unsubscribe from this list: send the line "unsubscribe linux-newbie"
in
> >>the body of a message to majordomo@vger.kernel.org
> >>More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >>Please read the FAQ at http://www.linux-learn.org/faqs
> >>
> >>
> >
> >-
> >To unsubscribe from this list: send the line "unsubscribe linux-newbie"
in
> >the body of a message to majordomo@vger.kernel.org
> >More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >Please read the FAQ at http://www.linux-learn.org/faqs
> >
> >
> >
>
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-newbie" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.linux-learn.org/faqs

guide to inline assembly

[palash kasodhan]

Hi
        I was looking for a tutorial / guide about mixing C and assembly
code. If some one can point a good guide , that would be great.


palash

RE: Switching between foreground and background

[Mariano Moreyra]

I don't know if that's the way to gain daemon behavior. If you fork twice,
your process stills attached to the controlling terminal.
I guess you could finish that terminal session without problem. But I think
that a real daemon has to detach him self from the controlling tty.
You can do that, like Raghu said, calling setpgrp and setsid and closing
stdout an err.
There is also a function in unistd that does all of this for you.

int daemon(int nochdir,int noclose); (see "man daemon")

Don't know if exists in all unix or linux distros. But it seems to work.
Saludos.

Manuk


-----Mensaje original-----
De: linux-c-programming-owner@vger.kernel.org
[mailto:linux-c-programming-owner@vger.kernel.org]En nombre de John T.
Williams
Enviado el: Martes, 23 de Septiembre de 2003 13:07
Para: rvk@gsecone.com; John T. Williams
CC: Silambu Chelvan; linux-newbie@vger.kernel.org;
linux-c-programming@vger.kernel.org
Asunto: Re: Switching between foreground and background


I have to admit that I don't know why, but every resource I've ever read
about causing programs to gain daemon behavior has involved forking 2 times
and then starting the program code.  If anyone here does know why, I'd would
be happy to hear it.



----- Original Message -----
From: "Raghuveer" <rvk@gsecone.com>
To: "John T. Williams" <jtwilliams@vt.edu>
Cc: "Silambu Chelvan" <silambu_mdu@yahoo.com>;
<linux-newbie@vger.kernel.org>
Sent: Tuesday, September 23, 2003 7:01 AM
Subject: Re: Switching between foreground and background


> John T. Williams wrote:
>
> >I think part of the problem here might be conceptual.
> >
> >If I understand what you want, you'd like, on a signal, for your program
to
> >go into the background (still running but no longer blocking the terminal
> >input/output). On another signal you would like the program to come back
to
> >the foreground.
> >
> >If this is the case, the problem you're facing is that the program being
in
> >the foreground and the background is actually part of the shell, not a
> >property of the program running.  Most Shells provide a way to switch
> >programs from the foreground to the background and back.
> >BASH for example I could type
> >
> >$>./myprogram
> >(cntr + Z) //suspends the current program and prings the prompt back
> >$>bg  (runs the program in the background)
> >
> >The only way that I know of to force a program to run in the background
in
> >the code is to make it a daemon which is done by forking twice
> >
> >int main(  ) {
> >   if(fork()==0)  {
> >            if( fork() == 0 )  {
> >                    program code starts here
> >             }
> >            exit(0);
> >    }
> >    exit(0);
> >}
> >
> >
> I don't feel it's required to fork() twice for making it a daemon, once
> is enough. Ya, but should use setpgrp() or setpid() and close stdin, out
> and err after the fork and go to infinite loop.
>
> -Raghu
>
> >
> >----- Original Message -----
> >From: "Silambu Chelvan" <silambu_mdu@yahoo.com>
> >To: <linux-newbie@vger.kernel.org>
> >Sent: Monday, September 22, 2003 6:48 AM
> >Subject: Switching between foreground and background
> >
> >
> >
> >
> >>Hi all,
> >>
> >>I have written some program with signal handler. Is
> >>this possible, if
> >>one of the signals registered with my program is
> >>raised, my program
> >>should goto background and should come to foreground
> >>when some other of the
> >>registered signal is raised. how to do it?
> >>
> >>Any function available to switch a process between
> >>foreground and
> >>background at runtime?
> >>
> >>with regards,
> >>M. SilambuChelvan
> >>
> >>
> >>__________________________________
> >>Do you Yahoo!?
> >>Yahoo! SiteBuilder - Free, easy-to-use web site design software
> >>http://sitebuilder.yahoo.com
> >>-
> >>To unsubscribe from this list: send the line "unsubscribe linux-newbie"
in
> >>the body of a message to majordomo@vger.kernel.org
> >>More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >>Please read the FAQ at http://www.linux-learn.org/faqs
> >>
> >>
> >
> >-
> >To unsubscribe from this list: send the line "unsubscribe linux-newbie"
in
> >the body of a message to majordomo@vger.kernel.org
> >More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >Please read the FAQ at http://www.linux-learn.org/faqs
> >
> >
> >
>
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-newbie" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.linux-learn.org/faqs

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Re: guide to inline assembly

[Progga]

On Tue, Sep 23, 2003 at 12:19:08PM -0400, palash kasodhan wrote:

>         I was looking for a tutorial / guide about mixing C and assembly
> code. If some one can point a good guide , that would be great.

 http://linuxassembly.org/


 There's exists a linux-assembly@vger.kernel.org mailing list too.


 Khoda Hafez
 Progga

gcc : cpp Memory Exhausted

[Matthew Studley]

Hi - I wonder whether anybody can help me?

I'm compiling some code on a robot (Slack 7.0, P 1).  I've compiled it many
times before on this platform with no problem.  Now when I make I get the
error:

cpp: Memory exhausted

...and the process fails
Anybody got any ideas?

regards

Matt

 ==============================================
Matthew Studley

The Intelligent Computer Systems Centre
Faculty of Computing, Engineering
        and Mathematical Sciences
Coldharbour Lane, Frenchay
BS16 1QY
United Kingdom

tel : 07092 306548
fax : 07092 306548

Re: gcc : cpp Memory Exhausted

[Matthew Studley]

I have 'solved' the problem; I was just compiling one of the source files, I
deleted all compiled output and recompiled all the source.  No problem!

This is bizarre!

I have no idea what was causing this though, and would really appreciate any
ideas!

regards

Matt

----- Original Message -----
From: Matthew Studley <matthew.studley@uwe.ac.uk>
To: <linux-c-programming@vger.kernel.org>
Sent: Wednesday, September 24, 2003 3:36 PM
Subject: gcc : cpp Memory Exhausted


> Hi - I wonder whether anybody can help me?
>
> I'm compiling some code on a robot (Slack 7.0, P 1).  I've compiled it
many
> times before on this platform with no problem.  Now when I make I get the
> error:
>
> cpp: Memory exhausted
>
> ...and the process fails
> Anybody got any ideas?
>
> regards
>
> Matt
>
>  ==============================================
> Matthew Studley
>
> The Intelligent Computer Systems Centre
> Faculty of Computing, Engineering
>         and Mathematical Sciences
> Coldharbour Lane, Frenchay
> BS16 1QY
> United Kingdom
>
> tel : 07092 306548
> fax : 07092 306548
>
>
>
>
> -
> To unsubscribe from this list: send the line "unsubscribe
linux-c-programming" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>
> This incoming email to UWE has been independently scanned for viruses and
any virus detected has been removed using McAfee anti-virus software
>
>
>

Re: gcc : cpp Memory Exhausted

[Luciano Miguel Ferreira Rocha]

On Wed, Sep 24, 2003 at 04:12:54PM +0100, Matthew Studley wrote:
> I have 'solved' the problem; I was just compiling one of the source files, I
> deleted all compiled output and recompiled all the source.  No problem!
> 
> This is bizarre!
> 
> I have no idea what was causing this though, and would really appreciate any
> ideas!

I don't know the exact reason, but I'l give some suggestions:

1. recursive #include, as when a.h #includes "b.h", and b.h #includes "a.h"
   or just a.h #includes "a.h"...

2. memory corruption. the compilation of all sources could had caused the
   corrupted cache to be discarded.

3. corruption of disk transfers
   (by means of an invalid selected DMA or ilegal cable)

Regards,
Luciano Rocha