Additive color mixing begins with black and ends with white; as more color is added, the result is lighter and tends to white. The RGB colors are light primaries and colors are created with light. Percentages of red, green, & blue light are used to generate color on a computer screen.
In shell scripting we often need to check if file or directory exists and take appropriate action. This post show you how to check it and how this check use in your script. For checking we will use file test operators -f for file and -d for directory, which return TRUE if file or directory exists. And here is output of the script.
The only exception is the first line in the file, where the comment is used to indicate which shell should be used (/bin/sh is the Bourne shell). It is always good practice to use comments to indicate what a script does; both in a header section at the top, and line by line if the code is at all complicated.