Reflectance values express the percentage of light that is reflected back from a surface, the difference having been absorbed or transmitted by the surface. Reflectances of room surfaces are used in determining coefficient of utilization values for luminaires.
The last three lines show you how to define your own awk function. The format is simple -- type function, then the function name, and then the parameters separated by commas, inside parentheses. After this, a { } code block contains the code that you'd like this function to execute.
This awk command checks for the string t4 in the 9th column and if it finds a match then it will print the entire line. The output of this awk command is -rw-r--r-- 1 pcenter pcenter 43 Dec 8 21:39 t4