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.
Test if a file exists with the BASH shell. Posted in Linux/Unix/BSD - Last updated Jan. 09, 2017. Often when shell scripting with BASH you need to test if a file exists (or doesn't exist) and take appropriate action. This post looks at how to check if a file exists with the BASH shell. To test if the /tmp/foo.txt file exists, you would do the following, changing the echo line to whatever action it is you want to take: if [ -f /tmp/foo.txt ] then echo the file exists fi.