How to suspend/hibernate from command line

First find out what states your system is supported:

$ cat /sys/power/state
mem disk

To suspend to ram:

# echo -n mem > /sys/power/state

To hibernate:

# echo -n disk > /sys/power/state

Ref: http://askubuntu.com/questions/1792/how-can-i-suspend-hibernate-from-command-line