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.
Save the file, calling it hello. Then make the hello file executable by typing: You can then run the script by simply typing hello. When you type hello, UNIX realises that this is a script, and runs the UNIX commands inside it (in this case, just the echo command).Naming Shell Script Files. You can give your shell scripts almost any name you like.hen make the hello file executable by typing: You can then run the script by simply typing hello. When you type hello, UNIX realises that this is a script, and runs the UNIX commands inside it (in this case, just the echo command).