Questions that baffled me

tar  grep find sed awk vim diff sort xargs ls pwd cd gzip unzip ps top tail kill rm cp mv cat chmod mkdir ifconfig uname -a whereis whatis man ping date wget http://www.thegeekstuff.com/2010/11/50-linux-commands/

Mostly they are the same as the root shell in both systems is bash http://superuser.com/questions/179368/how-does-macs-command-line-compare-to-linux If you want windows systems also to have this same shell then go for cygwin port for windows