To find all files that were modified since a specific time ago (i.e an hour ago, a day ago, 24 hours ago, a weeks ago and so on) in Unix environment, the find and lsof commands will come in handy. Following are some useful examples:
Files modified in the last 24 hours in the current directory
find . -mtime -1 -print
Files modified in the last X minutes in the current directory
find . -mmin -X -type f
Processes currently writing to files and what files are open for writing
lsof | grep -e "[[:digit:]]\+w"