Contents

• What's a Batch File, and What's it For?
• Creating, Editing and Running a Simple Batch File
• Batch File Documentation
• Echoing and Logging
• Adding parameters to a Batch File
• Batch Conditional Statements

Here are some of the things you can do with a batch file:

• Customize your system with programs that run at startup time
• Copy files from multiple directories to create backups
• Run a series of programs with one command
• Simplify complex commands by putting them in a file with a simple name
• Any repetitive series of commands that need to be run in several directories

Since batch files are simple ASCII text files, you don't need any special program to create them. You can use any text editor or word processor. The following section shows how...
 

To start, we need to run an editor. Simple editors (like DOS Edit and Windows Notepad) are usually easier and quicker than full-blown word processors (such as MS-Word or Word Perfect) because they load faster and they automatically save in ASCII format. The big word processors save, by default, in their own special format (which is really a sort of database!). In the SaveAs dialog box, you can specify saving as text or ASCII.

When our editor is running, we'll type in the directory command with the proper option switches:
 

Let's save the file with a simple name: d.bat

All batch files have the extension .bat which is necessary for the file to work in DOS.
(Remember: if  we use a word processor, we must make sure the file is saved as text.)

Running a batch file is simple: just type its name (the extension isn't needed) at a DOS prompt, and DOS will run it by executing all the commands in it. In this case, we should see something like this:
 
 

Note: in order to run a batch file, DOS has to be able to find it. It can do this if:

1. The batch file is in the current directory. (In this example, the batch file was in the root directory, and as you can see from the prompt, that's what the default directory was too.)
2. The batch file is in the "path". The path is a DOS listing of directories to look for executable programs, and can be set with the path command. For example:

path c:\; c:\dos; c:\windows

But there are things you can do in batch files that you can do nowhere else in DOS. Some of these are features that make batch files practical for a wide range of tasks that would otherwise be impractical. The rest of this module and the "Conditional Batch Commands in DOS" Module (Q12cd) introduce you to some of these batch commands.
 

This puzzlement can be avoided by including comments explaining what's going on. Like any computer programming situation, it takes a certain amount of self-discipline to actually put comments in; but once you get in the habit, you'll find it's easy and it really pays off down the road! Also, professional batch files (those created by technicians for use by other people) are usually required to have documentation within them.

How to Add Comments

1. The rem statement: Put the word rem at the beginning of a line, and the line will be ignored when you execute the batch file. The line can then be used to explain the batch file or some part of it.  ("Rem" is short for remark.)
2. The : colon: Lines beginning with the color : can be used as documentation, though the colon is also a label marker. (Labels, which are used in conditional batch statements, are points to which you can pass control within a batch file.)

What Comments to Add

• What the file is for, and how to use it
• Author's name or initials, and the date created and modified.

• If the batch file uses parameters (which we'll discuss soon), these should be explained.
• If conditional statements are used (and we'll touch on them, too), the condition tested should be explained.
• If the file is long and complicated, with several sections, the purpose of each section should be explained.
• In general, it's good to explain anything you can to make the process easier to understand.

An example of documentation

Echo

• Prevent the DOS commands from being shown (echoed) to the screen. Example:

echo off
• Make sure the DOS commands are being being shown on the screen. Example:

echo on
• Send messages to the screen. Example:

echo All done. Have a good day!

 Here is the output from running this batch file on the a: drive:
 

Notice the message at the end of the listing.

Notice also that the directory command itself doesn't show on the screen, but the command echo off does show. If you want to hide the echo off command, put the symbol @ in front of it, like this:
@echo off

Redirecting Output to Keep a Record

You can do this either at the DOS prompt or in a batch file. Let's modify the file to send output to a log file:
 

Let's run the modified file and look at the output:
 

This time, the d command didn't show any output on the screen. We were just returned to the DOS prompt. Using the type command, we can look at the file d.log to see our results. The output looks pretty much like any directory, but now it's in a file and can be displayed or edited in a text editor or word processor.
 

Let's take our directory batch file as an example. As we initially constructed it, it only does a listing of the current directory on the current disk. Also, we've sent the output to a log file. Either one of these can be modified if we use parameters. Here's how it works...

The Command Line with Parameters

d c:\temp prn
d a:\ a:floppy.lst
d c:\windows

Using Parameters in Batch Commands

Notice that we've added a comment statement briefly explaining what each parameter is supposed to do. Also, so the user will feel more confident of what's going on, we've added a screen echo saying what we're doing. The "All done" echo is directed to screen as well. (In the previous example, we appended it to the log file, remember?)

We now have a good, flexible batch file. To see what it can do, type it in and try it with several combinations of parameters!
 

Conditional statements can:

• Test for the existence of files
• Test to see if a parameter has a certain value or not
• Test the "return value" of a program

For exercises to practice creating simple batch files, see module Q11hd, "Creating Simple Batch Files in DOS".
 

Audience:

Objectives

• Create a batch file using a simple editor
• Save the batch file with the proper extension
• Discuss the use of command-line parameters
• Use more than one command-line parameter in a batch file
• Document the file with either REM, ECHO, or :
• Turn echo on and off

Module Q10cd: Introduction to Batch Files in DOS

Author:

Laurence J. Krieg

Institution:

Department of Computer Information Systems, Washtenaw Community College

History:

Original: 23 Mar 1998; links corrected 20 Dec 1999

Copyright:

Copyright © 1998, Laurence J. Krieg.

Instructors: You may point to this file in your Web-based materials.
Students: you may make a copy for your personal use.
All other uses: contact the author, Laurence J. Krieg for permission.