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 @Echo Off
 
 REM  DevPlayer@gmail.com
 REM  2011-Oct-3
 
 REM  This will run a python module if the version is correct.
 REM  the Python version is done before any modules are run.
 
 REM  Some benefits to this script are:
 REM     no files are created; avoids file write permission issues
 REM     no environment varibles are created; avoids permission issues
 REM     no Python modules are run; avoids syntax exceptions between
 REM         Python versions
 
 REM Some cons are:
 REM     This is a post Window 2000++ script; Win XP and later work.
 REM     This is not a unix/linux script although it can be adapted.
 REM     It is likely that not all Python interpreters support the
 REM     the -V option or push the -V output to stderr;
 REM         In which case just remove 2>&1
 REM     Assumes the output to be formatted like "Python x.y"
 REM     You have to run this script every time to launch your Python
 REM         app to benefit from this check.
 REM         So therefore you need to include it in your distribution
 
 REM  http://www.fpschultze.de/modules/smartfaq/faq.php?faqid=17
 REM  Read on 2011-Oct-3
 
 REM  Try this at Windows/DOS command prompt to see:
 REM     python.exe -V
 
 REM  This should send a string like "Python 2.7" without quotation marks,
 REM  to stderr (prints to console)
 
 REM  If your python.exe version doesn't support the -V option
 REM  this batch will still work.
 
 REM  This is not Python.
 REM  GENERALLY use " (double qoutes) in Windows DOS scripts/batch files.
 REM  Do not use ' (single quotes) unless the DOS command supports it
 
 REM  I only had one version of Python.exe on my system.
 REM  I don't know what text other versions of "python.exe -V" will return.
 
 REM  My version returns "Python 2.7" without the quotes,
 REM  even though I have version 2.7.0
 
 REM  Perhaps other people with other versions of Python can post what
 REM  their version of "python.exe -V" returns textually. I could then
 REM  update MS-Windows XP script.
 
 REM  Versions of Microsoft Windows OSes after MS-Windows XP Pro
 REM  will likely run this script fine.
 REM  It is very likely this script can be converted to a linux version.
 
 REM alternate: python -c "import sys; print sys.version_info" > pyver.txt
 
 FOR /F "tokens=1,2" %%G IN ('"python.exe -V 2>&1"') DO ECHO %%H | find "2.7" > Nul
 If Not ErrorLevel 1 Goto Python27
 
 REM  Here is the break down of that DOS line
     REM  "FOR /F", "IN", "DO", "ECHO" are internal DOS commands; ie part of cmd.exe
 
 	REM  "tokens=1,2"
 	REM     is a paramater for the "FOR /F" DOS command.
 	REM     It implicidly means "tokens=1,2 delims= "
 
 	REM     "delims= " means break down the string at every space character.
 	REM     So a string like "Python 2.7" will be broken down into:
 	REM     "Python" and "2.7"
 	REM     "delims" means delimiter
 
 	REM  "tokens=1,2" %%G
 	REM     means grab the "word zero" and grab "word one"
 	REM     in the string and put "word zero" (ie token 1) into variable
 	REM     %%G and "word one" (ie token 2) into variable %%H.
 
 	REM     Where did %%H come from?
 	REM     For each token in string, create a script varaible starting
 	REM     with %%G as the first varible name.
 	REM     This is an implicid feature of "FOR /F";
 	REM     max is 26 %%A-%%Z.
 
 	REM  IN
 	REM     means: in the string returned by the following -thing-
 
 	REM  q:\python27\python.exe -V
 	REM     tells python.exe to use the -V argument;
 	REM     which means print out the Python version
 	REM     to stderr and then exit (python.exe)
 
 	REM  2>&1
 	REM     means to tell the comand to redirect whatever is sent
 	REM     to stderr to stdout.
 
 	REM     In Lunix you could use just  2>&  I believe
 	REM     python.exe -V prints the version to stderr, not stdout.
 	REM     So this needs to be redirected to stdout to make it
 	REM     a string that can be used by a DOS SCRIPT
 
 	REM "python.exe -V 2>&1"
 	REM     The double quotation marks are needed
 	REM     because there are command parameters seperated by spaces
 	REM     and redirection, stderr to stdout, in the command
 
 	REM (' ..."python.exe.."  ')
 	REM     The parenthesis and single quotes tell the "FOR /F" command
 	REM     to execute the string as if the user typed it at the
 	REM     command prompt' and from that output of that execution
 	REM     put that output into a string usable by the "FOR /F" command.
 
 	REM DO
 	REM     "DO" is part of the "FOR /F" command
 
 	REM ECHO %%H
 	REM     write %%H to stdout; not that it is not %%G which would
 	REM     normally be the string "Python"
 
 	REM	| find "2.7" > Nul
 	REM     | == pipe
 	REM     find "2.7"
 	REM        is a DOS command that will search for a string "2.7"
 	REM        note the double quotes, no single quotes
 	REM        so pipe a string into find and compare to "2.7"
 	REM        and MOST importantly if it matches return with an
 	REM        Errorlevel of 1 if there is a match
 	REM    > Nul
 	REM        and send the search results, ie the output (not exit code)
 	REM        to the nul device instead of stderr or stdout.
 	REM        The user doesn't need to see that.
 
 	REM If Not ErrorLevel 1 Goto Python27
 	REM    means if "find"'s exit code is 1 then jump to the script
 	REM    section labeld Python27.
 	REM    A DOS lable is aline that starts with :<text>
 
 FOR /F "tokens=1,2" %%G IN ('"python.exe -V 2>&1"') DO ECHO %%H | find "2.4" > Nul
 If Not ErrorLevel 1 Goto Python24
 
 FOR /F "tokens=1,2" %%G IN ('"python.exe -V 2>&1"') DO ECHO %%H | find "2.5" > Nul
 If Not ErrorLevel 1 Goto Python25
 
 FOR /F "tokens=1,2" %%G IN ('"python.exe -V 2>&1"') DO ECHO %%H | find "2.6" > Nul
 If Not ErrorLevel 1 Goto Python26
 
 FOR /F "tokens=1,2" %%G IN ('"python.exe -V 2>&1"') DO ECHO %%H | find "2.7" > Nul
 If Not ErrorLevel 1 Goto Python27
 
 FOR /F "tokens=1,2" %%G IN ('"python.exe -V 2>&1"') DO ECHO %%H | find "2.8" > Nul
 If Not ErrorLevel 1 Goto Python28
 
 FOR /F "tokens=1,2" %%G IN ('"python.exe -V 2>&1"') DO ECHO %%H | find "2.9" > Nul
 If Not ErrorLevel 1 Goto Python29
 
 FOR /F "tokens=1,2" %%G IN ('"python.exe -V 2>&1"') DO ECHO %%H | find "3.0" > Nul
 If Not ErrorLevel 1 Goto Python30
 
 FOR /F "tokens=1,2" %%G IN ('"python.exe -V 2>&1"') DO ECHO %%H | find "3.1" > Nul
 If Not ErrorLevel 1 Goto Python31
 
 FOR /F "tokens=1,2" %%G IN ('"python.exe -V 2>&1"') DO ECHO %%H | find "3.2" > Nul
 If Not ErrorLevel 1 Goto Python32
 
 Goto :EOF
 
 REM  ------------------------------------
 ::Python 2.4 code
  :Python24
  echo FOUND 2.4
  python.exe my_python_app24.py
  goto :EOF
 
 ::Python 2.5 code
  :Python25
  echo FOUND 2.5
  python.exe my_python_app25.py
  goto :EOF
 
 ::Python 2.6 code
  :Python26
  echo FOUND 2.6
  python.exe my_python_app26.py
  goto :EOF
 
 ::Python 2.7 code
  :Python27
  echo FOUND 2.7
  python.exe my_python_app27.py
  goto :EOF
 
 :: Python 2.8
  :Python28
  echo Python 2.8 found
  python.exe my_python_app28.py
  goto :EOF
 
 :: Python 2.9; doesn't exist yet
  :Python29
  echo Python 2.9 found
  python.exe my_python_app29.py
  goto :EOF
 
 :: Python 3.0
  :Python30
  echo Python 3.0 found
  python.exe my_python_app30.py
  goto :EOF
 
 :: Python 3.1
  :Python31
  echo Python 3.1 found
  python.exe my_python_app31.py
  goto :EOF
 
 :: Python 3.2
  :Python32
  echo Python 3.2 found
  python.exe my_python_app32.py
  goto :EOF
 
 ::EOF
 :EOF