find

Find files modified within the last 6hrs i.e. 0.25 of 1 day
find /home/chris -type f -mtime -0.25

Find files where name (case insensitive) matches ‘*.exe’
find ~/.nuget/packages -iname "*.exe"

Find directories where name starts with ‘site’
find . -type d -name 'site*'

Find files by text in the file
find . -type f -name "*.java" -exec grep -il string {} \;
-i: ignore case
-l: show filenames, not the match.