diff -aurN a/imediff2 b/imediff2
--- a/imediff2	2018-10-20 13:36:19.000000000 -0400
+++ b/imediff2	2021-03-03 10:03:31.121774492 -0500
@@ -167,19 +167,19 @@
 def read_lines( filename ):
   global assume_empty
   try:
-    fp = file( filename )
+    fp = open( filename )
     l = fp.readlines()
     fp.close()
     return l
-  except IOError, (error, message):
-    if error == errno.ENOENT and assume_empty:
+  except IOError as e:
+    if e.errno == errno.ENOENT and assume_empty:
       return ""
     else:
-      sys.stderr.write(_("Could not read '%s': %s\n") % (filename, message))
+      sys.stderr.write(_("Could not read '%s': %s\n") % (filename, e.strerror))
       sys.exit(3)
 
 def strip_end_lines( txt ):
-  return string.replace(string.replace(txt,"%c"%10,""),"%c"%13,"")
+  return txt.replace("%c"%10,"").replace("%c"%13,"")
 
 def main(stdscr, lines_a, lines_b, start_mode):
   global sel, active_chunks, x,y, lines, textpad, contw,conth
@@ -283,7 +283,7 @@
         active_chunks.append( [j, j+len(line_list), i] )
 
       for l in line_list:
-        lines.append( [string.expandtabs(strip_end_lines(l)),
+        lines.append( [strip_end_lines(l).expandtabs(),
           decor, color_pair] )
         j+=1
 
@@ -332,9 +332,9 @@
   def sel_next( dir ):
     global sel, active_chunks
     if dir == 'up':
-      rng = range(sel-1, -1, -1)
+      rng = list(range(sel-1, -1, -1))
     else:
-      rng = range(sel+1, len(active_chunks))
+      rng = list(range(sel+1, len(active_chunks)))
     for j in rng:
       if active_chunks[j][1] > y and active_chunks[j][0] < y+winh:
         sel = j
@@ -487,7 +487,7 @@
     elif c == ord('h') or c == ord('?') or c == curses.KEY_HELP:
       helpw = 0
       helph = 0
-      for l in string.split(helptext(), "%c"%10):
+      for l in helptext().split("%c"%10):
         helpw = max(helpw, len(l))
         helph += 1
       helppad = curses.newpad(helph+2, helpw+2)
@@ -502,7 +502,7 @@
     elif c == ord('q') or c == curses.KEY_CANCEL:
       quitw = 0
       quith = 0
-      for l in string.split(quittext(), "%c"%10):
+      for l in quittext().split("%c"%10):
         quitw = max(quitw, len(l))
         quith += 1
       quitpad = curses.newpad(quith+2, quitw+2)
@@ -571,33 +571,33 @@
 try:
   opts, args = getopt.getopt(sys.argv[1:], "hmuo:abcNtV",
     ["help","mono","unresolved","output=", "template", "version", "new-file"])
-except getopt.GetoptError, e:
-  print _("Error: ") + str(e)
-  print usagetext()
+except getopt.GetoptError as e:
+  print((_("Error: ") + str(e)))
+  print(usagetext())
   sys.exit(2)
 
 for o, a in opts:
   if o in ("-h", "--help"):
-    print usagetext()
+    print((usagetext()))
     sys.exit()
   elif o in ("-t", "--template"):
     try:
       with open(config_file, 'w') as f:
-        print >>f, "# Configuration for imediff2: (Erase this file to reset)"
-        print >>f, "# <command_key_in_action> <command_key_in_manpage>"
-        print >>f, "# edit only first character of each line to 'a'...'z'"
-        print >>f, "#"
+        print(("# Configuration for imediff2: (Erase this file to reset)"), file=f)
+        print(("# <command_key_in_action> <command_key_in_manpage>"), file=f)
+        print(("# edit only first character of each line to 'a'...'z'"), file=f)
+        print(("#"), file=f)
         for k in kcvalues:
-          print >>f, "%s %s" % (k , k)
+          print(("%s %s" % (k , k)), file=f)
     except:
-      print "%s not writable, aborting" % config_file
+      print(("%s not writable, aborting" % config_file))
     sys.exit()
   elif o in ("-V", "--version"):
-    print "%s %s" % (PACKAGE, VERSION)
+    print(("%s %s" % (PACKAGE, VERSION)))
     sys.exit()
 
 if len(args)<2:
-  print usagetext()
+  print((usagetext()))
   sys.exit(2)
 
 for o, a in opts:
@@ -692,14 +695,14 @@
     assert( not editor is None )
     try:
       (of, of_name) = tempfile.mkstemp(prefix='imediff2')
-      os.write( of, output )
+      os.write( of, output.encode() )
       os.close(of)
       time.sleep(0.1) # make the change visible - many editor look a lot like imediff2
       editor_ret = os.system('%s %s' % (editor, of_name))
       time.sleep(0.1)
       if editor_ret == 0:
         new_b_lines = read_lines(of_name)
-        if string.join(new_b_lines, '') == output:
+        if ''.join(new_b_lines) == output:
           chunk_mode = 'old'
         elif new_b_lines != lines_a:
           lines_b = new_b_lines
@@ -707,8 +710,8 @@
         else:
           chunks = 'old'
       os.unlink(of_name)
-    except IOError, (error, message):
-      sys.stderr.write(_("Could not write to '%s': %s\n") % (of_name, message));
+    except IOError as e:
+      sys.stderr.write(_("Could not write to '%s': %s\n") % (of_name, e.strerror));
 
   if not launch_editor:
     break
@@ -719,11 +722,11 @@
 else:
   try:
     if ofile is not None:
-      of = file(ofile, 'wb')
-      of.write( output )
+      of = open(ofile, 'wb')
+      of.write( output.encode() )
       of.close()
     sys.exit(0)
-  except IOError, (error, message):
-    sys.stderr.write(_("Could not write to '%s': %s\n") % (ofile, message));
+  except IOError as e:
+    sys.stderr.write(_("Could not write to '%s': %s\n") % (ofile, e.strerror));
 
 sys.exit(3)