What is my PATH and what do I need it for?

(originally posted 3/5/07)
______________________________________________
From: SD-Jim Sawyer
Sent: Monday, March 05, 2007 12:55 PM
To: SD-Dave Brann; SD-Kevin Bennett; SD-Emily Ligotti; NS-Geoff Skipton; NS-Jess Bardin; CD-Jason Moline
Subject: What is my PATH and what do I need it for?

Hey gang,

Sorry it's been a while since the last blog… They ain't billable after all! But this one just came up today and I figured it was a good refresher.

Back in the dark days of software development, we had to use the Command Prompt to compile and build our applications. Real Men and Women used the keyboard only and the fastest typer was clearly the alpha geek. There was no pointy arrow on the screen. "Menus"? Bah who needs em. To "Rebuild All"… you typed in separate commands to compile each source code file, link them together, and create the executable.

(I won't mention the even darker days of punch cards)

Today, great IDEs like Visual Studio (and pretty good IDEs like in our simulation software) have made things a helluva lot easier on us developers. However, even in 2007, there are still times we'll want to use the command prompt.

For example, for you AnyLogic developers, the Java SDK contains a number of potentially useful utilities that are run from the command line. (e.g. I was looking at http://java.sun.com/developer/technicalArticles/Security/Signed/ this morning)Same with Visual Studio. And for Arena developers, the command-line compilers model.exe, expmt.exe, and linker.exe can still be useful for debugging certain esoteric Arena error messages. I'm sure there's some use in Automod too.

One of the key concepts in running applications from the command line is the idea of setting the PATH. The PATH is a system setting that specifies the set of directories used to search for executable files. This means that instead of typing
> C:\Program Files\Java\jdk1.6.0\bin\javac.exe MyClass
I only have to type
> javac MyClass.

Your PATH normally comes set up with some default paths to Windows folders, and some installation packages will also update the PATH. You can modify the PATH yourself from within Windows too.

1. On the Start menu, right-click My Computer and select Properties
2. Select the Advanced tab.
3. Click on Environment Variables.
4. In the second group box called System Variables, scroll down until you see a setting for PATH.
5. Click on the Edit button and type in the location of the new folders.

For example, I added the folders for the Java JDK and the Siman compilers to my PATH, as you can see below. The other folders were added when various programs were installed.

C:\Program Files\Rockwell Software\RSCommon;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;C:\Program Files\Intel\Wireless\Bin\;C:\Program Files\ThinkPad\ConnectUtilities;C:\Program Files\Common Files\Lenovo;C:\Program Files\Lenovo\Client Security Solution;C:\Program Files\Microsoft SQL Server\90\Tools\binn\;C:\Program Files\Autodesk\DWG TrueView\;C:\Program Files\Java\jdk1.6.0\bin;C:\Program Files\Rockwell Software\Arena 11.0

Well hopefully you'll be spending the majority of your work time in modern IDEs, but if you ever decide to go old school, we can get you a copy of "4DOS"...



James T. Sawyer
Senior Analyst
TranSystems | Automation Associates, Inc.