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Setting the path with a batch file

Listing 1 shows the contents of a batch file named 1359-1050-01.bat containing four commands that :

  1. Reduce the clutter on the output screen (echo off) .
  2. Temporarily set the path to the location of the file named python.exe on my computer.
  3. Attempt to execute the Python script file named 1359-1050-01.py, which will be discussed later in this module.
  4. Pause onscreen and wait to be dismissed with the prompt "Press any key to continue . . ."
Listing 1 . Setting the path temporarily with a batch file.
echo off path=%path%;"C:\Program Files (x86)\Python34"python 1359-1050-01.py pause

The second command in Listing 1 is the important command for thissection of this module. It will temporarily set the path to the indicated folder. If you elect to use this approach, you will need toreplace the text inside the double quotes with the path to the folder containing the file named python.exe on your computer.

This approach appends the new path onto the environment variable named path on a temporary basis. It goes away as soon as you respond to the pause statement at the end or otherwise close the command-line window that appears when you execute the batch file.

Create a script file

Once you have the path variable properly set, or you know how to set it temporarily in a batch file, use the text editor of your choice andcreate a file named 1359-1050-01.py that contains the Python programming statements shown in Listing 2 . (You can give the file any name that you chooseprovided that the extension is .py and provided that you properly reflect the name in the third line of the batch file shown in Listing 1 .)

Listing 2 . Contents of the file named 1359-1050-01.py.
a=2 b=3a=2*a b=3*bc=a+b print(c)

You should recognize all of the statements in Listing 2 . Note, however, that in a script, they are not preceded by an interactive prompt (>>>).

Store this file in any folder on your hard drive. You may want to create a new directory for the sole purpose of storing Python script files.

Then create the corresponding batch file with the contents shown in Listing 1 and save it in the same folder as the script file. (If you have permanently set your path to support Python, you can omit the path command in Listing 1 .)

Run your script file

Once you have accomplished the above, double-click the batch file to execute it. The batch file will temporarily set the path and attempt to run your script.If all goes well, a command-line window will appear on your screen with contents similar to that shown in Figure 1 . (Note that I deleted some of the text on the first line for brevity. Your first line will be different anyway.)

Figure 1 . Screen output from running the script named 1359-1050-01.py.
M:\Baldwin\AA-School\...>echo off 13Press any key to continue . . .

The correct output

If you go back to the script file in Listing 2 and do the arithmetic, you will see that the output value of 13 produced by the program is correct.

If you got an output value of 13, -- congratulations -- you have just written and executed your first Python script. If not, try to figure out why.

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Source:  OpenStax, Itse 1359 introduction to scripting languages: python. OpenStax CNX. Jan 22, 2016 Download for free at https://legacy.cnx.org/content/col11713/1.32
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