Skunkware 5/Skunkware 5.iso/man/cat.1/perlipc.1

Text File | 1995-07-25 | 8KB | 265 lines

     PPPPEEEERRRRLLLLIIIIPPPPCCCC((((1111))))  UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV ((((RRRReeeelllleeeeaaaasssseeee 0000....0000 PPPPaaaattttcccchhhhlllleeeevvvveeeellll 00000000))))  PPPPEEEERRRRLLLLIIIIPPPPCCCC((((1111))))



     NNNNAAAAMMMMEEEE
          perlipc - Perl interprocess communication

     DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
          The IPC facilities of Perl are built on the Berkeley socket
          mechanism.  If you don't have sockets, you can ignore this
          section.  The calls have the same names as the corresponding
          system calls, but the arguments tend to differ, for two
          reasons.  First, Perl file handles work differently than C
          file descriptors.  Second, Perl already knows the length of
          its strings, so you don't need to pass that information.

          CCCClllliiiieeeennnntttt////SSSSeeeerrrrvvvveeeerrrr CCCCoooommmmmmmmuuuunnnniiiiccccaaaattttiiiioooonnnn

          Here's a sample TCP client.

              ($them,$port) = @ARGV;
              $port = 2345 unless $port;
              $them = 'localhost' unless $them;

              $SIG{'INT'} = 'dokill';
              sub dokill { kill 9,$child if $child; }

              use Socket;

              $sockaddr = 'S n a4 x8';
              chop($hostname = `hostname`);

              ($name, $aliases, $proto) = getprotobyname('tcp');
              ($name, $aliases, $port) = getservbyname($port, 'tcp')
                  unless $port =~ /^\d+$/;
              ($name, $aliases, $type, $len, $thisaddr) =
                              gethostbyname($hostname);
              ($name, $aliases, $type, $len, $thataddr) = gethostbyname($them);

              $this = pack($sockaddr, &AF_INET, 0, $thisaddr);
              $that = pack($sockaddr, &AF_INET, $port, $thataddr);

              socket(S, &PF_INET, &SOCK_STREAM, $proto) || die "socket: $!";
              bind(S, $this) || die "bind: $!";
              connect(S, $that) || die "connect: $!";

              select(S); $| = 1; select(stdout);












     Page 1                                          (printed 6/30/95)






     PPPPEEEERRRRLLLLIIIIPPPPCCCC((((1111))))  UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV ((((RRRReeeelllleeeeaaaasssseeee 0000....0000 PPPPaaaattttcccchhhhlllleeeevvvveeeellll 00000000))))  PPPPEEEERRRRLLLLIIIIPPPPCCCC((((1111))))



              if ($child = fork) {
                  while (<>) {
                      print S;
                  }
                  sleep 3;
                  do dokill();
              }
              else {
                  while (<S>) {
                      print;
                  }
              }

          And here's a server:

              ($port) = @ARGV;
              $port = 2345 unless $port;

              use Socket;

              $sockaddr = 'S n a4 x8';

              ($name, $aliases, $proto) = getprotobyname('tcp');
              ($name, $aliases, $port) = getservbyname($port, 'tcp')
                  unless $port =~ /^\d+$/;

              $this = pack($sockaddr, &AF_INET, $port, "\0\0\0\0");

              select(NS); $| = 1; select(stdout);

              socket(S, &PF_INET, &SOCK_STREAM, $proto) || die "socket: $!";
              bind(S, $this) || die "bind: $!";
              listen(S, 5) || die "connect: $!";

              select(S); $| = 1; select(stdout);

              for (;;) {
                  print "Listening again\n";
                  ($addr = accept(NS,S)) || die $!;
                  print "accept ok\n";

                  ($af,$port,$inetaddr) = unpack($sockaddr,$addr);
                  @inetaddr = unpack('C4',$inetaddr);
                  print "$af $port @inetaddr\n";

                  while (<NS>) {
                      print;
                      print NS;
                  }
              }





     Page 2                                          (printed 6/30/95)






     PPPPEEEERRRRLLLLIIIIPPPPCCCC((((1111))))  UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV ((((RRRReeeelllleeeeaaaasssseeee 0000....0000 PPPPaaaattttcccchhhhlllleeeevvvveeeellll 00000000))))  PPPPEEEERRRRLLLLIIIIPPPPCCCC((((1111))))



          SSSSyyyyssssVVVV IIIIPPPPCCCC

          Here's a small example showing shared memory usage:

              $IPC_PRIVATE = 0;
              $IPC_RMID = 0;
              $size = 2000;
              $key = shmget($IPC_PRIVATE, $size , 0777 );
              die if !defined($key);

              $message = "Message #1";
              shmwrite($key, $message, 0, 60 ) || die "$!";
              shmread($key,$buff,0,60) || die "$!";

              print $buff,"\n";

              print "deleting $key\n";
              shmctl($key ,$IPC_RMID, 0) || die "$!";

          Here's an example of a semaphore:

              $IPC_KEY = 1234;
              $IPC_RMID = 0;
              $IPC_CREATE = 0001000;
              $key = semget($IPC_KEY, $nsems , 0666 | $IPC_CREATE );
              die if !defined($key);
              print "$key\n";

          Put this code in a separate file to be run in more that one
          process Call the file _t_a_k_e:

              # create a semaphore

              $IPC_KEY = 1234;
              $key = semget($IPC_KEY,  0 , 0 );
              die if !defined($key);

              $semnum = 0;
              $semflag = 0;

              # 'take' semaphore
              # wait for semaphore to be zero
              $semop = 0;
              $opstring1 = pack("sss", $semnum, $semop, $semflag);

              # Increment the semaphore count
              $semop = 1;
              $opstring2 = pack("sss", $semnum, $semop,  $semflag);
              $opstring = $opstring1 . $opstring2;

              semop($key,$opstring) || die "$!";




     Page 3                                          (printed 6/30/95)






     PPPPEEEERRRRLLLLIIIIPPPPCCCC((((1111))))  UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV ((((RRRReeeelllleeeeaaaasssseeee 0000....0000 PPPPaaaattttcccchhhhlllleeeevvvveeeellll 00000000))))  PPPPEEEERRRRLLLLIIIIPPPPCCCC((((1111))))



          Put this code in a separate file to be run in more that one
          process Call this file _g_i_v_e:

              #'give' the semaphore
              # run this in the original process and you will see
              # that the second process continues

              $IPC_KEY = 1234;
              $key = semget($IPC_KEY, 0, 0);
              die if !defined($key);

              $semnum = 0;
              $semflag = 0;

              # Decrement the semaphore count
              $semop = -1;
              $opstring = pack("sss", $semnum, $semop, $semflag);

              semop($key,$opstring) || die "$!";




































     Page 4                                          (printed 6/30/95)