http://www.wikihow.com/Find-a-File-in-Linux

find / -type f -iname “libphp5.so”

find / -type d -iname “ibdata1”

find / -type f -iname “*arcconf”

grep -R ‘AllowNoPassword’ /

egrep ‘User’ /etc/apache2/apache2.conf

grep DocumentRoot /etc/apache2/apache2.conf

To find files larger than 100MB, use this command:
find / -type f -size +100000k -exec du -h {} \;

Search within files for specific text: https://stackoverflow.com/questions/16956810/how-do-i-find-all-files-containing-specific-text-on-linux

grep –exclude-dir={dir1,dir2,*.dst} -rnw ‘</path/to/somewhere/>’ -e “<pattern/text>”

grep –exclude-dir={/sys} -rnw ‘/etc’ -e “debug.log”