Search for a string in multiple files
grep is a common command used on unix for searching. This is a very useful tool and provides powerful options. One such option is to search for a string in multiple files in the current directory and sub directories. The command is : grep -rl "search string" /usr -r stands for search recursively in current directory and sub directory. -l suppress the display of additional information and just outputs the file names. /usr refers to root folder under which the search happens.