1+ #include <stdio.h>
2+ #include <stdlib.h>
3+ #include <fcntl.h>
4+ #include <unistd.h>
5+ #include <sys/wait.h> // For wait, waitpid
6+ 7+ #define PORTNUM 1500 // Port > 1024 because program will not work not as root.
8+ #define NUMBER_OF_PROCESSES 2
9+ #define EXIT_FAILURE 1
10+ 11+ // Compilation:
12+ // gcc -std=gnu99 "00 - Processes.c" -o processes
13+ 14+ // Task:
15+ // Use fork to create a child process.
16+ 17+ void main (int argc , char * argv [])
18+ {
19+ printf ("0 Enter to main!\n" );
20+ for (int i = 0 ; i < NUMBER_OF_PROCESSES ; i ++ )
21+ {
22+ pid_t pid ;
23+ int status ;
24+ switch (pid = fork ())
25+ {
26+ case -1 :
27+ perror ("1 Error of calling fork" );
28+ exit (EXIT_FAILURE );
29+ case 0 :
30+ printf ("1 CHILD: Child process %d!\n" , getpid ());
31+ printf ("2 CHILD: Parent PID %d!\n" , getppid ());
32+ printf ("3 CHILD: Wait 10 seconds...\n" );
33+ sleep (10 );
34+ printf ("4 CHILD: Exit!\n" );
35+ exit (EXIT_FAILURE );
36+ default :
37+ printf ("1 PARENT: Parent process %d!\n" , getpid ());
38+ printf ("2 PARENT: Child PID %d\n" , pid );
39+ printf ("3 PARENT: Wait until child calls exit()...\n" );
40+ waitpid (pid , & status , 0 );
41+ printf ("4 PARENT: Child exit code: %d\n" , WEXITSTATUS (status ));
42+ printf ("5 PARENT: Exit!\n" );
43+ }
44+ }
45+ 46+ printf ("1 Exit main!\n" );
47+ exit (0 );
48+ }
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