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.
If you are debugging a shell script, and you want to see what your script is doing, you can duplicate one of the important lines in your script and insert an echo in front of one of the duplicates.ou can uncomment the command set-x and try the script with the command. The argument to the shell script is 2, so $1 is evaluated and returns the value 2.. This makes the argument to awk the string print {$2} and the second column is printed out.