Introduction

Up to this point, we have primarily entered the data through the command line. While this is fine for small scripts, it does not provide the means to obtain and store information. To accomplish this, we need to read and write to the file system.

File access is a basic requirement for dynamic programs. Whether it's a text-based configuration file or images to display, most programs use the file system as the storage and retrieval location. All storage needs have—historically and continually—relied on the file system.

Although we will be dealing with strings in the coming sections, the requirements for accessing any type of file, from the string data to images, remain the same.

In the following sections, for the majority of the examples, we will be accessing the file system to read and write the data to a file. To accomplish this, you will need to launch your Tcl shell appropriately, based on your operating platform and follow the instructions.