check to see if you have swap partitions defined by consulting /etc/fstab. If you do then
grep swap /etc/fstab
Returns something like this.
UUID=14a0f7b9-dabb-4296-b0e7-013527a7d82d none swap sw 0 0
If one is defined you can check that it is being used by the system:
swapon -s
returns:
Filename Type Size Used Priority /dev/sda6 partition 1004020 215532 -1
If one is defined but not in use the obvious thing to do is check that it is formatted as a swap partition:
sudo fdisk -l /dev/sda
returns
[..snipped..] /dev/sda5 3842 6595 22121473+ 83 Linux /dev/sda6 6596 6720 1004031 82 Linux swap / Solaris
If it is a swap partition, ready it for use and turn it on. At this point, you might see any errors that prevented its use.
su - mkswap /dev/sda6 swapon /dev/sda6
You can now check that the partition is being used using the “swapon -s” command we saw above.
Add an entry to /etc/fstab to have this swap partition loaded at bootup. You can replace the “UUID=xxx” part from above with “/dev/sda6”; so the entry would look like this:
/dev/sda6 none swap sw 0 0
If you didn't define a swap partition earlier, then you'd have to create one, or point swap to a regular file (which is a little less efficient, but probably sufficient).
Using a static partition for swap is wasteful - so I tend to configure my systems with LVM, and allocate a swap partition in that.
If I'm not using LVM then a simple file is sufficient, since a system actually using swap is probably already broken. This is how I'd set it up:
su - dd if=/dev/zero of=/swap.file bs=1024k count=1 mkswap -f /swap.file echo "/swap.file none swap sw 0 0 " >> /etc/fstab swapon -a