Note that with the 2.6 Linux kernel, swap files are just as fast as swap partitions. Even though I recommend using a swap partition. ;)
Step #1: Create Storage FileLogin as the Root User, open a terminal window and follow the instructions below.
NOTE: You need to use the dd command to create swap file.
Type the following command to create 512MB swap file (1024 * 512MB = 524288 block size):
ximena@anneke:~$ dd if=/dev/zero of=/swapfile bs=1024 count=524288
if=/dev/zero : Read from /dev/zero file.
Note that /dev/zero is a special file in that provides as many null characters to build storage file called /swapfile
of=/swapfile1 : Read from /dev/zero write stoage file to /swapfile.
bs=1024 : Read and write 1024 bytes at a time.
count=524288 : Copy only 523288 input blocks.
Step #2: Set Up a Linux Swap Area
Type the following command to set up a Linux swap area in the file we created in Step #1:
ximena@anneke:~$ mkswap /swapfile
NOTE: The mkswap command is used to set up a Linux swap area on a device or in a file.
Setup correct file permission for security reasons, enter:
ximena@anneke:~$ chown root:root /swapfile
ximena@anneke:~$ chmod 0600 /swapfile
A world-readable swap file is a huge local vulnerability. The above command make sure only root user can read/write to the file. Finally, activate /swapfile1 swap space immediately, enter:
ximena@anneke:~$ swapon /swapfile
To activate /swapfile1 after Linux system reboot, add entry to /etc/fstab file. Append the following line:
/swapfile swap swap defaults 0 0
Next time Linux comes up after reboot, it enables the new swap file for you automatically.
Step #3 Checking if the Swap is Activatedximena@anneke:~$ free -m
You will be able to see the new swap area activated ;)