Search all of a site's files for a string in Linux in seconds

Web Developer + Linux Skills = Easy Life
 
grep -R "?f=video" *
 
 
Recursively search all of the files for the string ?f=video.
 
Why is this helpful?  
 
Say you found a bug with ?f=video?  The logs only show ?f=video.
 
Search every single line of code on your website with 1 command.  
 
It will tell you the exact line of file it finds the string. 
 
Open that file and fix the code.