xsession skeleton

fimplate.py

@@ -1,11 +1,7 @@
 #!/usr/bin/python
-
-import sys
-import os
-import re
+import sys,re,os
 from argparse import ArgumentParser 
 from argparse import RawTextHelpFormatter
-
 def setup_options():
     parser=ArgumentParser(description="""Template Filler
     
@@ -16,6 +12,8 @@ def setup_options():
 == Value file/Value pair example: ==
 [[name]]=John 
     """,formatter_class=RawTextHelpFormatter)
+    parser.add_argument("-e",action="store_true",dest="env",default=False,
+                      help="Use the environment to replace ${env} style variables.")
     parser.add_argument("-f",action="store",dest="file",
                       help="File name to read keys/values.")
     parser.add_argument("-p",action="append",dest="values",default=[],
@@ -49,21 +47,20 @@ def parse_arguments(args):
         pairs.append( (tokens[0], tokens[1].decode('string_escape')) )
     return pairs
 
-def main():
-    options=setup_options();
-    pairs=[]
-    if options.file!=None:
-        pairs.extend(parse_file(options.file))
-    pairs.extend(parse_arguments(options.values))
-    if options.template==None:
-        in_reader=sys.stdin
-    else:
-        in_reader=open(options.template,'rb')
-    for l in in_reader:
-        for p in pairs:
-            l=l.replace(p[0],p[1])
-        sys.stdout.write(l)
-        
-if __name__ == "__main__":
-    main()
-
+options=setup_options();
+pairs=[]
+if options.file!=None:
+    pairs.extend(parse_file(options.file))
+pairs.extend(parse_arguments(options.values))
+if options.template==None:
+    in_reader=sys.stdin
+else:
+    in_reader=open(options.template,'rb')
+for l in in_reader:
+    for p in pairs:
+        l=l.replace(p[0],p[1])
+    if options.env:
+        var_list=[m.group(0) for m in re.finditer('\${[^ ]+}', l)]
+        for v in var_list:
+            l=l.replace(v,os.environ.get(v[:-1][2:],""))
+    sys.stdout.write(l)