How to use fork() in unix? Why not something of the form fork(pointerToFunctionToRun)?

Question

I am having some trouble understanding how to use Unix\'s fork(). I am used to, when in need of parallelization, spawining threads in my application. It\'s always s

Answer 1

You fork whenever you want to more than one thing at the same time. It’s called multitasking, and is really useful.

Here for example is a telnetish like program:

#!/usr/bin/perl
use strict;
use IO::Socket;
my ($host, $port, $kidpid, $handle, $line);

unless (@ARGV == 2) { die "usage: $0 host port" }
($host, $port) = @ARGV;

# create a tcp connection to the specified host and port
$handle = IO::Socket::INET->new(Proto     => "tcp",
                                PeerAddr  => $host,
                                PeerPort  => $port)
       or die "can't connect to port $port on $host: $!";

$handle->autoflush(1);              # so output gets there right away
print STDERR "[Connected to $host:$port]\n";

# split the program into two processes, identical twins
die "can't fork: $!" unless defined($kidpid = fork());

if ($kidpid) {                      
    # parent copies the socket to standard output
    while (defined ($line = <$handle>)) {
        print STDOUT $line;
    }
    kill("TERM" => $kidpid);        # send SIGTERM to child
}
else {                              
    # child copies standard input to the socket
    while (defined ($line = )) {
        print $handle $line;
    }
}
exit;

See how easy that is?