Creating a batch file: How to write your own .bat file

cmd.exe, also known as a Command Prompt, is one of oldest software components in Windows. For decades, this command-line processor has been used to make direct changes to Microsoft operating systems. Batch files (also known as .bat files) are closely associated with Command Prompt. These files contain native commands that cmd.exe uses to process a sequence of commands. We’ll explain the unique features of these useful scripts and show you how to create, save, and run batch files yourself.

A batch file (also known as a .bat file or batch script) is a text file that the Windows cmd.exe command line processor executes as a batch job. Command Prompt assumes both the role of interpreter and runtime environment. Put simply, a batch file is a computer program or script containing data or tasks that are processed sequentially by Command Prompt.

Batch files allow you to use and run ordinary CMD commands with cmd.exe as the interpreter and runtime environment. You can also use comments, labels, variables, conditions, and queries when writing a batch file. To convert text files to batch files, you have to use the .bat extension in newer Microsoft systems. The .cmd extension was common in Windows NT and OS/2.

Creating your own batch files is useful for automating the execution of recurring command sequences. These sequences might include login processes or what is known as TSR programs (Terminate and Stay Resident) that you want to run continuously as background processes. In the following sections, we’ll explain the tools you need to create batch files and show you how to create, save, and run your own batch files.

You don’t have to learn complicated programming language to create batch files. But you do need to know common system commands and understand how they work in batch files. That’s why you should familiarize yourself with some commands before writing your first script. Here are the most important commands to learn:

• ECHO: Turns on the on-screen text display for executed commands
• @ECHO OFF: Turns off the on-screen text display for executed commands
• START: Runs a file with its default associated application
• REM: Indicates a comment line
• MKDIR/RMDIR: Creates or deletes a directory
• DEL: Deletes selected file(s)
• COPY: Copies selected file(s)
• TITLE: Sets the title of the CMD window

An easy introduction to the art of creating batch files is to write a simple script that creates multiple directories on a selected disk on your computer. For example, if you create and run a batch file with the following input, it will create two directories named “Example1” and “Example2” on drive C:

With the above step-by-step guide, you can create a wide variety of batch files with an unlimited number of different commands. However, scripts that you can use more frequently are definitely more useful in the long run. We’ll conclude with two examples of batch files with long-term value to illustrate the possibilities of batch processing with Windows Command Prompt.

The following example shows how useful batch files can be for creating regular back-ups of any directory:

When you create and run a batch file containing the line shown above, use the “xCOPY” command to copy the contents from the “source folder” to the “back-up folder.” You’ll need to adjust the directories containing these two folders accordingly. The three parameters at the end have the following effect:

• /m: Ensures that only updated files are copied so that files that have already been backed up don’t have to be copied again during further back-up operations.
• /e: Indicates that the back-up includes all subdirectories in the specified directory.
• /y: Suppresses prompting to confirm that you want to overwrite an existing destination file that was changed since the last backup.

The above backup program allows you to copy the source files from the source folder to the destination folder. You can also create a batch file that distributes source data to multiple destination folders, in which case you can use the file type as a selection criterion. To do this, you need a for loop, which allows a command to run repeatedly with a variable argument:

The batch code shown above ensures that:

• all files in the source directory with the .doc and .txt extensions are moved to the “Text” back-up folder.
• all files in the source directory with the .jpg, .png and .bmp extensions are moved to the “Images” backup folder.
• only updated files are copied.
• the confirmation prompt is always suppressed.