get filename programmatically

vignere.py

@@ -0,0 +1,68 @@
+#!/usr/bin/python3
+import sys, getopt, os
+
+def encrypt(string,key):
+    lowerstr=string.lower()
+    print("Encrypting "+lowerstr+" with key "+key)
+    strnums = []
+    keynums = []
+    resultnums = []
+    resultstring = ""
+    for c in lowerstr:
+        strnums.append(ord(c)-97)
+    print(strnums)
+    for c in key:
+        keynums.append(ord(c)-97)
+    print(keynums)
+    keypointer=0
+    for n in strnums:
+        resultnums.append((n+keynums[keypointer])%26)
+        keypointer = (keypointer+1) % (len(key))
+    print(resultnums)
+    for c in resultnums:
+        resultstring = resultstring+chr(c+97)
+    print(resultstring)
+
+def decrypt(string,key):
+    lowerstr=string.lower()
+    print("Decrypting "+lowerstr+" with key "+key)
+    strnums = []
+    keynums = []
+    resultnums = []
+    resultstring = ""
+    for c in lowerstr:
+        strnums.append(ord(c)-97)
+    print(strnums)
+    for c in key:
+        keynums.append(ord(c)-97)
+    print(keynums)
+    keypointer=0
+    for n in strnums:
+        resultnums.append((n-keynums[keypointer])%26)
+        keypointer = (keypointer+1) % (len(key))
+    print(resultnums)
+    for c in resultnums:
+        resultstring = resultstring+chr(c+97)
+    print(resultstring)
+
+def main(argv):
+    key = ""
+    try:
+        opts, args = getopt.getopt(argv,"hk:e:d:",["key=","encrypt=","decrypt="])
+    except getopt.GetoptError:
+        print(os.path.basename(__file__)+' -k <key> -e <plain text>')
+        print(os.path.basename(__file__)+' -k <key> -d <encrypted text>')
+        sys.exit(2)
+    for opt, arg in opts:
+        if opt == '-h':
+            print(os.path.basename(__file__)+' -k <key> -e <plain text>')
+            print(os.path.basename(__file__)+' -k <key> -d <encrypted text>')
+            sys.exit()
+        elif opt in ("-k", "--key"):
+            key = arg
+        elif opt in ("-e", "--encrypt"):
+            encrypt(arg,key)
+        elif opt in ("-d", "--decrypt"):
+            decrypt(arg,key)
+if __name__ == '__main__':
+    main(sys.argv[1:])