Problem with asynchronous notification

rajesh_b · 09-17-2004, 03:45 AM

I am trying to write a program which checks whether a file is modified or not. if it is modified it must exit. I have written the following code. but the program is not exiting even though i modified the file. i am using f_notify of fcntl to receive notfification.

#define _GNU_SOURCE
#include<unistd.h>
#include<fcntl.h>
#include <stdio.h>
#include <signal.h>

main()
{

int fd;
int sig_hand();
signal(SIGIO,sig_hand);
fd = open("/root/br.xml", O_RDONLY);
fcntl(fd,F_SETOWN,getpid());
fcntl(fd,F_SETFL,FASYNC);
fcntl(fd, F_NOTIFY, DN_MODIFY);

for(;

{
printf("Here i am waiting for the file to be changed\n");

}

}
int sig_hand()
{
printf("File is changed, i m exiting ");
exit(0);
}

any help plz
rajesh

Sadrul · 09-17-2004, 05:10 AM

from the man-page of `fcntl':

Code:

       F_NOTIFY
              (Linux  2.4  onwards)  Provide  notification  when  the directory
              referred to by fd or  any  of  the  files  that  it  contains  is
              changed.

so you have to open the dir rather than the file itself.

-- Adil

rajesh_b · 09-17-2004, 07:58 AM

thankx for u r advice.
Is there any way to find out whether a file has been modified or not and getting that notificatoin asynchronously.