#!/usr/bin/env python
import sys,os,shutil
#-----------------------------------------------------------------------
def replace_string(file,oldstr,newstr):
#
# Replace all occurrences of "oldstr" in oldfile to "newstr" in newfile.
# Note oldfile and newfile may be the same, i.e., overwrite oldfile. 
#
# Read contents first, then close input file.
#
  file_read = open(file,'r')
  contents = file_read.read()
  file_read.close()
# print contents
#
# Open output file and change chars per line.
#
  fw = open(file,'w')
  for line in contents:
    newline = line.replace(oldstr,newstr)
    fw.write(newline)
  fw.close()
#-----------------------------------------------------------------------
#
oldstr = ';'
newstr = '!'
for file in sys.argv[1:]:
# print 'file = ',file,': Changing "',oldstr,'" to ',newstr
  if os.path.isfile(file):
    answer = raw_input('Overwrite file '+file+' (y/n/q, default=n)? ')
    if answer == 'q': sys.exit()
    if answer == 'y':
      replace_string(file,oldstr,newstr)
      print 'Overwrote file ',file,' with "',oldstr,'" replaced by "',newstr,'"'
    elif answer == 'n' or answer == '':
      newfile = file+'.new'
      shutil.copyfile(file,newfile)
      replace_string(newfile,oldstr,newstr)
      print 'Wrote file ',newfile,' with "',oldstr,'" replaced by "',newstr,'"'
    else:
      print 'File ',file,' is unchanged.'
  else:
    print '>>> Cannot find file ',file
    continue