1. Count the number of files in the current directory:
   ls -1 | wc -l
   ls -l | grep -v ^l | wc -l
   Reference: http://www.tldp.org/HOWTO/Bash-Prompt-HOWTO/x700.html
2. Remove all the files with name XXX* in the current directory:
   find . -name “XXX*” -print0 | xargs -0 -I {} rm {}
3. List the total size of each folder (-s is to list only total size):
   du -sh directory
   du -h directory

TO BE UPDATED