How is WEXITSTATUS(stat_val) obtaining the value 37? I know that WEXITSTATUS is used to obtain the child's exit code and the exit_code variable is assigned 37 in this program but i don't see how this WEXITSTATUS is working. Is the WEXITSTATUS function written to look through the child process code for an exit_code variable?
Code:
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <stdio.h>
int main()
{
pid_t pid;
char *message;
int n;
int exit_code;
printf(“fork program starting\n”);
pid = fork();
switch(pid)
{
case -1:
perror(“fork failed”);
exit(1);
case 0:
message = “This is the child”;
n = 5;
exit_code = 37;
break;
default:
message = “This is the parent”;
n = 3;
exit_code = 0;
break;
}
for(; n > 0; n--) {
puts(message);
sleep(1);
}
//This section of the program waits for the child process to finish.
if (pid != 0) {
int stat_val;
pid_t child_pid;
child_pid = wait(&stat_val);
printf(“Child has finished: PID = %d\n”, child_pid);
if(WIFEXITED(stat_val))
printf(“Child exited with code %d\n”, WEXITSTATUS(stat_val));
else
printf(“Child terminated abnormally\n”);
}
exit(exit_code);
}