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13.2.3. Creating a Swap File

To add a swap file:
  1. Determine the size of the new swap file in megabytes and multiply by 1024 to determine the number of blocks. For example, the block size of a 64 MB swap file is 65536.
  2. At a shell prompt as root, type the following command with count being equal to the desired block size:
    dd if=/dev/zero of=/swapfile bs=1024 count=65536
  3. Setup the swap file with the command:
    mkswap /swapfile
  4. To enable the swap file immediately but not automatically at boot time:
    swapon /swapfile
  5. To enable it at boot time, edit /etc/fstab to include the following entry:
    /swapfile swap swap defaults 0 0
    The next time the system boots, it enables the new swap file.
To test if the new swap file was successfully created, use cat /proc/swaps or free to inspect the swap space.