To find string into several files, you can use the Windows Powershell and the Get-ChildItem (Dir) command-let as following:

dir <<v>base_directory> -I <<v>file_extensions[]> -R | Select-String <<v>strings_to_search[]>

E.g.:

dir dir c:\fso -I *.txt, *.log -R | Select-String fail, success, pending

This command looks for the string “success” and “pending” into all sub directory of the folder “c:\fso”