=====Swap===== 

Linux needs swap if you run out of ram its choices are

  * out of memory killer will kill a process (loads of processes are excluded)
  * it will clear out a page from cache to disk
  * it will use swap space

use **free** to see memory and swap usage

to create a swap use a free partition and then use the 

<code> mkswap partition_name</code>

you then have to add it to fstab once there you can use

<code> swapon -a </code>

to enable it use

<swapon -s </code> to check it