No child process error while using system() command

Hi
I am getting errno:10 No child process error while using system() command. I tried doing wait(NULL) in parent but could not get success.
Can you please suggest me a way to resolve this error. Its urgent.

Thanks in advance.

Regards
Rasika

Rasika, welcome to Java Ranch!

What do you mean by "system() command"?

Showing the code in question might also help.

Hey thanks....
Actually I'm using system() command to get the output of "df" command in child process but I'm getting error as "No child process".

I'm redirecting output of system() command to file and then reading from it in parent process. I tried using waitpid() in parent process. But it didn't help.

Here is a piece of code.

int main(void)
{
char buf[1024];
FILE* fp1=NULL;
int ierr;
char strcmd[]="df -km %s 2>&1 | grep -v Mounted 2>&1 > output.txt"

if ((pid = fork()) < 0)    /* child process is created by a call to fork(). it returns the process                               ID of the child  */
	{
         
		  printf("***ERROR DOING FORK*** \n");

}
else if (pid == 0)
	{
         	printf("***NOW IN CHILD PROCESS*** \n");
         
		system(strcmd);     
          	   
			      
		 ierr = errno;
         /* error */
         printf("unable to execute '%s', errno %d:%s\n", strcmd, ierr, strerror(ierr));
         printf("***CLOSE CHILD PROCESS*** \n"); 
		 		
        } 
	
	
	printf("Parent process executes here...");
	   waitpid(-getpid(), &stat, 0);  //wait for child
		// wait(NULL);
	  /* hold SIGCHLD until we're done to prevent it breaking out of fgets() loop */
      	printf("holding SIGCHLD\n");
     	sighold(SIGCHLD);

/* get lines from command and extract percentage used */
        printf("calling fgets()\n");
	fp1=fopen("output.txt","r");

while (fgets(buf,sizeof(buf),fp1))
  	{
			 char *pu = NULL;
			 pu = strstr(buf, "%");
			 if (pu != NULL)
			 {
				/* get percentage used and free */
				printf("used = %d%%\n",atoi(pu-3));
				prcfre = 100 - atoi(pu-3);
				/* break as we've got what we needed */
						 
				break;
		         }
	}
	 
}

Thanks and Regards
Rasika.

Ahah! You never said your app was written in C! I assumed Java. I'll defer to a C expert for the answer.

By the way, please use the 'code' tags when posting source, makes it much easier to read.

Raiska --

This code isn't complete (many variables like stat, prcfre, and pid are undeclared), so I imagine there are all sorts of things that might go wrong with those declarations; but I think the main problem is that the syntax for your df command is wrong. That "%s" looks like it's intended to be a replaceable parameter -- i.e., a format string for the sprintf() command. You're not replacing the parameter with anything, though, and so df is going to fail. The "no child process" could definitely come from that.

So do you want df to report the usage of a particular filesystem, or all filesystems, or what?