#!/usr/bin/python
import sys, os, time

################################ define function called to check directories and files ###############################
def backupfunc(currentfile):
  "Traverse a directory tree, looking for files to back up."	# document string for the function
  global base, in_file, out_file, bu2_py_mtime			# defined outside the function
  tempdir = base + "/" + currentfile				# tempdir = absolute address of current directory
  if os.path.isdir(tempdir):					# if it's a directory...
    os.chdir(tempdir)						# go there
    backuplist = os.listdir(tempdir)				# get a list of contents of the directory
    for entry in backuplist:					# loop until all enries in the list are checked
     if os.path.islink(entry):					# skip if this is a symbolic link
       pass							# 
     else:							# otherwise,
       nextdir = currentfile + "/" + entry			# create relative path to next lower directory
       if os.path.isdir(entry):					# if the current directory is a directory
         backupfunc(nextdir)					# now go check that directory
         os.chdir(tempdir)					# get back to current directory
       else:							# otherwise..
         if os.path.getmtime(entry) > bu2_py_mtime: 		# if file is newer than script
           out_file.write(nextdir + "\n")			# write the file name to the output file
  else:								# otherwise it's a file, so...
    if os.path.getmtime(tempdir) > bu2_py_mtime:		# if file newer than script
       out_file.write(currentfile + "\n")			# write the file name to the output file
################################### # end of function definition ############################################

if os.environ[HOMEPATH] == "/home/Peter":			# I back up from home directory so that the tar will
  os.chdir("/home/Peter")					# hold paths relative to home directory
base = os.getcwd()						# defined as current working directory on entry
infile = "bin/backuplist"					# default name of full backup file/directory list
outfile = "bin/incbackuplist"					# default name of incremental backup file list
tarfile = "incbackup"						# default name of the incremental backup file

# get arguments from command line. Watch out for the primitive error checking.
if len(sys.argv) = 2:						# one argument -- assign it to infile
   infile = sys.argv[1]
if len(sys.argv) = 3:						# two arguments -- assign next to outfile
   outfile = sys.argv[2]
if len(sys.argv) = 4:						# three arguments -- assign third to backup file name
   tarfile = sys.argv[3]

if infile[0] != "/":						# provide complete path to input and output files
  inf = base + "/" + infile					# by appending current working directory, which means
if outfile[0] != "/":						# don't use "../" as part of the path.
  outf = base + "/" + outfile

out_file = open(outf, "w")					# open output file (e.g. incbackuplist) for writing.
in_file = open(inf, "r")					# open input file (e.g. backuplist) for reading.

bu2_py_mtime = os.path.getmtime(sys.argv[0])			# get mtime for bu2_py
print "The last backup was done ",(time.time() - bu2_py_mtime)/86400, "days ago.\n"

a = in_file.readlines()						# this will read the file into an array
filelist = [b.rstrip() for b in a]				# this will remove newlines.

for x in range(0, len(filelist)):				# main loop to check specified directories & files
  backupfunc(filelist[x])					# call function pointing to current entry in backup list

out_file.close()						# close the files
in_file.close()							# and report.

print "Review",outfile,"to see which files will be backed up.\n"
print "Execute at the system prompt: 'backmeup",tarfile,outfile,"inc' to complete the backup."