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Full Discussion: problem implementing fork
Top Forums Programming problem implementing fork Post 302356176 by dheerajsuthar on Thursday 24th of September 2009 07:14:12 PM
Old 09-24-2009
problem implementing fork
Hi,
I was honing my linux programming skill when this nuisance started bugging me. I wanted to create an empty file creator program. While creating a large file it must print # for progress bar. But the output shows it happening reverse way. ie. first it copies file and shows the progress bar(although the bar is filled completely thus showing that parent process is working correctly). Kindly help me in putting these progress # simultaneously to file copying. Thanks in advance.
Code:
Code:
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/wait.h>

static int status = 0;
void ding()
{
status =1;
}
int main(int argc, char* argv[])
{
int rc=0,fd,i,tem=0;
char c=' ';
int size= atoi(argv[1])*1024;
char *add=argv[2];

pid_t pid;
pid = fork();
switch(pid){
case -1:
perror("Error creating fork\n");
exit(1);

case 0:
/*child process*/
{
fd = open(add,O_WRONLY|O_CREAT,0666);
if (fd<0)
{
printf("Error creating file\n");
exit(1);
}
for(i=1;i<=size;i++)
{
tem = write(fd, &c, 1);
rc += tem;
}
printf("rc: %d\n",rc);
if(rc!=size)
perror("Error allocating size.\n");
else
kill(getppid(),SIGALRM);

close(fd);
exit(0);
}
/*child process ends*/
}
/*parent process*/
(void) signal(SIGALRM,ding);
while(1){
printf("#");
sleep(1);
if(status)
{
printf("\ndone.\n");
exit(1);
}
}
}

Output:
Code:
dheeraj@dheeraj-machine:~/linux_pro$ ./a.out 1000 temp

hangs for some time. then:
Code:
rc: 1024000
###########################
done.

Clearly these # should have been printed along with file copy process. But don't know why its not.
 

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