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Perl, the Practical Extraction and Report Language, is Larry Wall's catch-all scripting language that has become nearly ubiquitous on UNIX systems. Of the many UNIX scripting languages available, Perl is the only one with built-in Internet networking support. For example, here a short script (taken verbatim from the Perl manual page), that implements a simple Internet server, which listens for TCP connections on port 2345 and prints anything it receives on standard output:
#!/usr/bin/perl
($port) = @ARGV;
$port = 2345 unless $port;
require 'sys/socket.ph';
$sockaddr = 'S n a4 x8';
($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 () {
print;
print NS;
}
}
An online version of the Perl manual best describes how to use it. Tom Christenson maintains the Perl Language Home Page, and Yahoo has a Perl page.