Redhat I always use command

Last update, 25 April 2011
This is not only for Redhat, but for most of Linux machine (I think)

Source of this command is from here. I keep using them
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/4/html/Step_by_Step_Guide/s1-manipulate-current.html
http://redhat.activeventure.com/71/gettingstartedguide/s1-managing-working-with-files.html

This is a good reference for VI - Visual Editor (Command line interface for text editor)
http://www.cs.colostate.edu/helpdocs/vi.html

Check folder size

du -hs /path/to/directory

Check harddisk space

df

List all the content within the current folder (or path)

ls OR ls -all

Remove file

rm thefilename.txt

Move file

mv thefilename.txt /home/asipo/

Delete directory and all its content

rm -rf /home/asipo/backupdocuments

Zip a file or folder

zip -r iWantTheZipFileNameToBeLikeThisOkay.zip theActualFileName.txt

Unzip a file (not sure for folder)

unzip thefilename.zip

Change folder owner

chown -R asipo.asigroup '/var/www/smellynomore/app/tmp'

Change folder permission

chmod -R 777 '/var/www/smellynomore/app/tmp'

Copy all except one folder
Taken from here http://www.unix.com/unix-dummies-questions-answers/44010-copy-entire-folder-except-one.html

shopt -s extglob
cp -r A/!(B) dest_dir

Execute bin file

chmod u+x qt-sdk-linux-x86-opensource-2010.05.1.bin

./qt-sdk-linux-x86-opensource-2010.05.1.bin

Connect to server and control it (Telnet / SHH I think)

ssh -p 22 asipi@langit.com.my