find - search for files in a directory hierarchy
Hint:
find WHERE WHAT
Find files larger than 1GB
$ find . -type f -size +1G
Find files smaller than 1GB
$ find . -type f -size -1G
Find ALL files larger than 100MB and sort by size
$ find / -type f -size +100M 2>/dev/null -exec ls -sh {} \; | sort -h
For ethical hacking
Find files with SUID
find / -perm -u=s -type f 2>/dev/null find / -perm -4000 -type f 2>/dev/null
On Windows, use dir to search for files/directories: dir filename /s