#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <semaphore.h>
int main( int argc,char** argv )
{
 sem_t *id;
 pid_t child;
 int status;
 id = sem_open( "szlaban",O_CREAT,S_IRUSR|S_IWUSR,0 );
 switch( (int)(child=fork()) )
 {
 case -1: perror("...fork()..."); exit( 1 ); break;
case 0: ...kod dla potomka
printf("*** [%u] potomek czeka na semafor (%p)\n",(unsigned)getpid(),id);
sem_wait( id );
printf( "*** [%u] potomek zakończył\n",(unsigned)getpid() );
exit( 0 );
default: ...kod dla procesu nadrzędnego
printf( "*** [%u] ustawia semafor (%p)\n",(unsigned)getpid(),id );
sem_post( id );
if( !wait( &status ) ){ perror( "... wait()..." ); exit( 2 ); }
else
{
printf( "*** [%u] wygląda, że to wszystko\n",(unsigned)getpid() );
sem_close( id ); sem_unlink( "szlaban" );
}
}
 return 0;
}