What is the Command Line?

Command Line Explained

There are several ways to begin the running/execution of an application.  In today's Windows operating systems, most people start software programs the same way, by double or single clicking on the appropriate Icon, or menu item in your Windows shell.  However, the same can be accomplished by commanding the operating system to run the program with textual commands within what is called the 'command prompt'.  In Windows 2000 you can begin the command prompt by going to the "Start\Programs\Accessories\Command Prompt" menu item.

The command prompt goes further back than the days of DOS (Disk Operating System) where all things were done by textual commands. COPY, DELETE, MOVE are just several of the available programs that could be executed.  COPY for example, required additional information to run, like what to copy and where.  Informing the COPY program of this additional information is done by passing command line parameters.   So for example if I wanted to copy the source file: "C:\MyDirectory\MyFile.TXT" to the directory "D:\MyTemp\" one would type the following into the command prompt:

"copy c:\MyDirectory\MyFile.TXT D:\MyTemp" <RETURN>

In addition to the programs provided by the operating system, programs such as WordDocDiff and WordConverterEXE can also be launched in this manner.

Batch Files

In many cases a whole series of commands is issued by the user through the command line interface.  If this is done often, it can become laborious to retype the commands in every time.  For this reason, the command prompt has the ability to process batch files.  Batch files are text files with the commands to be issued to the command prompt.  The operating system reads from the top of the batch file, and ends at the bottom, executing each line along the way.  The operating system recognizes batch files as having the *.BAT extension. 

So for example if I wanted to copy 3 files to 3 different locations on a frequent basis I might have to type in the following commands in the command prompt (every time):

"copy c:\MyDirectory\MyFile.TXT D:\MyTemp" <RETURN>

"copy c:\MyDirectory2\MyFile2.TXT D:\MyTemp2" <RETURN>

"copy c:\MyDirectory3\MyFile3.TXT D:\MyTemp3" <RETURN>

The smart thing to do however, is to launch notepad, type the 3 commands as shown above, and save it as Copy3Files.BAT.  Then, any time I want to do those 3 copies, I would simply type:

"Copy3Files.BAT"

at the command prompt.  Double clicking on the batch file within the Windows Explorer also will initiate the batch process.

Leveraging The Command Line

So, how can the fact that a 3rd party program allows for command line execution help me?  As shown in the 3 file copy example above, using the command line facilitates the automation of time consuming processes.  Furthermore, there are applications which allow for the launching of other applications through this mechanism.  It is all about saving time and reducing keystrokes and clicks.