Find

Find searches the directory tree rooted at each given file name by evaluating the given expression from left to right, according to the rules of precedence, until the outcome is known (the left hand side is false for and operations, true for or), at which point find moves on to the next file name.

Find

Find a file based on the filename:

   find /dir/ -name "filename.php"

This lists all files which have been modified per unit of time (showing 30 days here):

    find /dir/ -mtime +30

Find can be piped into other commands in case the other commands can't measure or see files:

   find . -type f -exec du -a {} + | sort -n -r