#include <stdio.h>
#include <unistd.h>

int main()
{
 int p[2];  /* p is pointer to array of two ints */
 int rc;

 rc = pipe( p );
 printf( "%d %d\n", p[0], p[1] );

 if ( rc < 0 ) {
   perror( "pipe() failed" );
   return 1;
 }

 rc = fork();  /* create child */

 if ( rc < 0 ) {
   perror( "fork() failed" );
   return 1;
 }

 if ( rc == 0 ) {   /* child */
   dup2( p[1], 1 );   /* redirect stdout (1) to pipe */
   close( p[0] );  /* don't let this child process access p[0] */
   execlp( "/bin/ls", "ls", "-l", NULL );
 }
 else /* parent */
 {
   dup2( p[0], 0 );   /* redirect stdin (0) to pipe */
   close( p[1] );
   execlp( "/usr/local/bin/less", "less", NULL );
 }

 return 0;
}