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diff --git a/Demo/comparisons/systemtest.py b/Demo/comparisons/systemtest.py
new file mode 100755
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+++ b/Demo/comparisons/systemtest.py
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+#! /usr/local/bin/python
+
+# 3)  System Test
+# 
+#     Given a list of directories, report any bogus symbolic links contained
+#     anywhere in those subtrees.  A bogus symbolic link is one that cannot
+#     be resolved because it points to a nonexistent or otherwise
+#     unresolvable file.  Do *not* use an external find executable.
+#     Directories may be very very deep.  Print a warning immediately if the
+#     system you're running on doesn't support symbolic links.
+
+# This implementation:
+# - takes one optional argument, using the current directory as default
+# - uses chdir to increase performance
+# - sorts the names per directory
+# - prints output lines of the form "path1 -> path2" as it goes
+# - prints error messages about directories it can't list or chdir into
+
+import os
+import sys
+from stat import *
+
+def main():
+	try:
+		# Note: can't test for presence of lstat -- it's always there
+		dummy = os.readlink
+	except AttributeError:
+		print "This system doesn't have symbolic links"
+		sys.exit(0)
+	if sys.argv[1:]:
+		prefix = sys.argv[1]
+	else:
+		prefix = ''
+	if prefix:
+		os.chdir(prefix)
+		if prefix[-1:] != '/': prefix = prefix + '/'
+		reportboguslinks(prefix)
+	else:
+		reportboguslinks('')
+
+def reportboguslinks(prefix):
+	try:
+		names = os.listdir('.')
+	except os.error, msg:
+		print "%s%s: can't list: %s" % (prefix, '.', msg)
+		return
+	names.sort()
+	for name in names:
+		if name == os.curdir or name == os.pardir:
+			continue
+		try:
+			mode = os.lstat(name)[ST_MODE]
+		except os.error:
+			print "%s%s: can't stat: %s" % (prefix, name, msg)
+			continue
+		if S_ISLNK(mode):
+			try:
+				os.stat(name)
+			except os.error:
+				print "%s%s -> %s" % \
+				      (prefix, name, os.readlink(name))
+		elif S_ISDIR(mode):
+			try:
+				os.chdir(name)
+			except os.error, msg:
+				print "%s%s: can't chdir: %s" % \
+				      (prefix, name, msg)
+				continue
+			try:
+				reportboguslinks(prefix + name + '/')
+			finally:
+				os.chdir('..')
+
+main()