i have 2 executable files. From one of them i'm calling the other one. it is also executed correctly, but does not return 0.

why?

backup.c file :

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <unistd.h>
#include <mysql/mysql.h>


int main(int argc, char * argv[])
{


   if(!execl("/home/user1/exec_work/binary","/home/user1/exec_work/binary","serdar","ilter",NULL))
   {
      /* This line is not printed to the screen. */
      printf("0\n");
   }
   else
   {
      /* This line is not printed to the screen either. */
      printf("1\n");
   }

   return 1;

}

The other source file:

#include <stdio.h>
int main(int argc, char * argv[])
{

/* I see that this line is printed to the screen */
   printf("%s %s\n",argv[1],argv[2]);

   return 0;

}

You are using the wrong function family. exec() isn't supposed to return.

Use one of the spawn() functions instead.

Hope this helps.

I used spawnl instead of execl, but it gives compile time error

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <stdarg.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <mysql/mysql.h>

.....
spawnl(P_WAIT,"/home/user1/exec_work/binary","/home/user1/exec_work/binary","serdar","ilter",NULL);

it says:
`P_WAIT' undeclared (first use in this function)

what header file am i missing? If I put 1 instead of P_WAIT, this time it says that spawnl undeclared.

If you're using a POSIX system (like Linux), then you also need to read up on fork() and wait().

In pseudocode

if ( fork() == 0 ) {
  execl()
} else {
  wait()
}
int status;
int options;
...
switch (pid = fork()) {
        case -1: /* fork failed */
                printf("forked failed\n");
                exit(-1);
        case 0: /* child starts executing here */
                execl(...);
        default: /* parent starts executing here */
                waitpid(pid, &status, options);
                ...
}

You can then examine status, ans see how the child process has terminated,
and set options to wait for the child or not...

man waitpid for more details

Why type all the verbiage when you can just use spawnl()?

You need to #include <process.h> Hope this helps.

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