title: command to search string in linux environment
body: <p>i have unix directory path. this directory contains 5 sub-folders.
  under each subfolder, i have 10 files (similar). this sub folder means each site or location files.</p>
  
  <p>I want to search a particular number present in each five subfolder.</p>
  
  <p>i am currently using grep command which is useful to find string in a sub folder, but not in all sub folders</p>
  
  <p>grep -l search string *.
  this is performing for a sub folder.
  i want to do search for all five subfolders using one single command.</p>