DOS Batch File Scripting Tips That Work in Vista

Batch files have been around since the early Ms DOS days. They are text files that contain a list of command-line executables. They can be compared to UNIX shell scripting, but are much simpler. For a file to be recognized by command.com (Microsoft’s DOS shell) it needs to have a .bat extension.

• To print a message on the screen use the echo command. For example: echo Hello, World!

• By default the commands in a batch file are displayed at the prompt before being executed. To prevent this from happening start every command with an At sign ‘@’ or enter the following command at the top of the file: @echo off

• To use arguments passed to the batch file use the Percent sign ‘%’ followed by the argument’s number, for example to use the second and fourth arguments with echo: echo Second Arg: %2, Fourth Arg: %4

• To redirect the output to a new file use the Greater Than sign ‘>’. If the file exists it will be overwritten. Here is an example that will save the directory listing to a file called dirlist.txt: dir > dirlist.txt

• To append the redirected output to the end of an existing file use 2 Greater Than signs next to each other ‘»’. The following example appends another directory listing to the file from the previous example: dir » dirlist.txt

• To display the contents of a text file use the type command. Here is an example that displays the contents of the dirlist.txt file: type C:\dirlist.txt

• Conditional processing is done using the if else statement. Following is an example that checks if a file exists before displaying its contents:

if exist C:\dirlist.txt (
    type C:\dirlist.txt
) else (
    echo The file does not exist.
)