Adding log extractor

exercises/205_sustained_link/scripts/extract_tbeam_log_segment.pl

@@ -0,0 +1,51 @@
+#!/usr/bin/env perl
+#
+# $Id$
+# $HeadURL$
+#
+# Example:
+#   ./extract_tbeam_log_segment.pl DAN_raw_20260604_094435.log 20260604_211500 20260604_211900
+#
+# Redirect example:
+#   ./extract_tbeam_log_segment.pl DAN_raw_20260604_094435.log 20260604_211500 20260604_211900 \
+#     > DAN_segment_20260604_211500_211900.log
+#
+
+use strict;
+use warnings;
+
+my $LOGDIR = "/home/jlpoole/logs";
+
+my ($logname, $start, $end) = @ARGV;
+
+die "Usage: $0 LOGNAME START_TIME END_TIME\n"
+  unless defined $logname && defined $start && defined $end;
+
+die "START_TIME must look like YYYYMMDD_HHMMSS or YYYYMMDD_HHMMSS.xxx\n"
+  unless $start =~ /^\d{8}_\d{6}(?:\.\d+)?$/;
+
+die "END_TIME must look like YYYYMMDD_HHMMSS or YYYYMMDD_HHMMSS.xxx\n"
+  unless $end =~ /^\d{8}_\d{6}(?:\.\d+)?$/;
+
+die "END_TIME must be greater than START_TIME\n"
+  unless $end gt $start;
+
+my $path = "$LOGDIR/$logname";
+
+open my $fh, '<', $path
+  or die "Cannot open $path: $!\n";
+
+while (my $line = <$fh>) {
+    my ($stamp) = split /\s+/, $line, 2;
+
+    next unless defined $stamp;
+    next unless $stamp =~ /^\d{8}_\d{6}(?:\.\d+)?$/;
+
+    # Include start time, exclude end time.
+    print $line if $stamp ge $start && $stamp lt $end;
+
+    # Optional early exit because logs are chronological.
+    last if $stamp ge $end;
+}
+
+close $fh;