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 first line of the script determines the shell to start. The first two characters of the first line should be #! , then follows the path to the shell that should interpret the commands that follow.Blank lines are also considered to be lines, so don't start your script with an empty line.he first two characters of the first line should be #! , then follows the path to the shell that should interpret the commands that follow. Blank lines are also considered to be lines, so don't start your script with an empty line.