An easy way to search for a word within directory contents is the ‘rgrep’ command:
rgrep “word“ /some/directory
If you don’t have the rgrep command installed on your distribution, you can use grep with the following flags:
grep -rnw “word” /some/directory
grep -rnw “Failed password” /var/log/auth.log
will list you all unsuccessful login attempts on your machine.