Added timetest.pl as an example for using hooks.

tmcd/common/hook-examples/timetest.ns

+set ns [new Simulator]
+source tb_compat.tcl
+
+set NodeA [$ns node]
+
+tb-set-node-os $NodeA FEDORA10-STD
+
+tb-add-node-service-hook "rc.isup" -script "/proj/tbres/duerig/timetest.pl" -op boot -whence every -env boot -point post -fatal 0
+
+# Go!
+$ns run

tmcd/common/hook-examples/timetest.pl

+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+my $debug = 0;
+if (@ARGV >= 1 && $ARGV[0] eq '-d') {
+    $debug = 1;
+    shift @ARGV;
+}
+
+#die "Usage: $0 -d TOLERANCE boot\n" unless @ARGV == 1;
+
+my $TOLERANCE = 0.5;
+if (scalar(@ARGV) > 1) {
+    $TOLERANCE = $ARGV[0];
+}
+
+my $NTP_SERVER = "ops.emulab.net";
+
+my $offset;
+my $output = '';
+open NTP, "/usr/sbin/ntpdate -q ops.emulab.net | ";
+while (<NTP>) {
+    $output .= $_;
+    next unless /.+?: [a-z]+ time server .+? offset ([-+.\d]+) sec/;
+    $offset = $1;
+}
+
+unless (defined $offset) {
+    print STDERR "*** ERROR: Unable to get offset from ntpdata\n";
+    print STDERR "NOTE: ntpdate output\n";
+    print STDERR $output;
+    exit 2;
+}
+
+if (abs($offset) > $TOLERANCE) {
+    print STDERR "*** ERROR: offset of $offset greater than $TOLERANCE\n";
+    print "FAILED: offset of $offset greater than $TOLERANCE\n";
+    exit 1;
+} else {
+    print "PASSED: offset of $offset within tolerance of $TOLERANCE\n";
+}
+