Enable GD on Linux

1. install
yum install php-gd

2. restart service
/etc/init.d/httpd restart

Linux Tips

1. vi hangs
Ctrl-s inside vi editor freezes the shell as it locks the terminal output
Ctrl-q to resume terminal output

2. vi command 
http://www.computerhope.com/unix/uvi.htm
<ESC> : end insert mode and return to command mode
ZZ : exit vi

dd : delete an entire line
3dd : delete 3 lines
u : undo last change

:set number : show line number
nG: go to line n
Shift+G : go to bottom

3. scp copy files between servers
scp [[user@]from-host:]source-file [[user@]to-host:][destination-file]


4. Find File
find / -name 'xxx.xx'