Add file type swap to linux

To add swap to linux machine:

1. Create a swap file. Size depends on your preference. Let's say we want to create a swap file with 8GB size (1024 x 1024 x 8 = 8388608).

# dd if=/dev/zero of=/swapfile bs=1024 count=8388608

where if is source, of is output file for dd to write to which is /swapfile in this case, bs is read/write byte size at a time and count is number of blocks.

2. Once created, make it a swap file

# mkswap /swapfile

3. Activate your swap file

# swapon /swapfile

4. Check your newly created swap space using free or top

# free -m

or

# top

5. To make it appear even after reboot, put it into fstab

# echo "swapfile swap swap defaults 0 0" >> /etc/fstab

It will look like this:

# cat /etc/fstab 
...
/swapfile1 swap swap defaults 0 0
...