Can swap space be created or destroyed after installation?

[Thrillhouse]

I have a ~800 MB partition formatted as ext3 that I'm currently not using. I was wondering if there's any way to make that into swap space now, after installation, or if it's something that can only be done during the installation process. I didn't create any swap space when I first installed my machine because the space was initially unformatted but I'm thinking now that it might be useful, better than having that much space go to waste. I'd also like to be able to destroy that partition and merge it back into my /home directory if needed. Is this feasible?

[Javasnob]

Yeah, you can use mkswap, swapon, and /etc/fstab to incorporate the partition into swap.

[Thrillhouse]

OK, after reading some man pages I tried this:

su
mkswap -c /dev/hda4
Setting up swapspace version 1, size = 1044602 kB
no label, UUID=19ac7ff8-9357-4be6-9b38-4c9abf229892
swapon -s /dev/hda4

But it hasn't been recognized yet:

free -m
             total       used       free     shared    buffers     cached
Mem:          1011        451        559          0          2        170
-/+ buffers/cache:        279        732
Swap:            0          0          0

However, GParted identifies the partition as linux-swap so I know it's at least allocated correctly. Do I need to reboot or something for the changes to take affect? Thanks for your help.

[Thrillhouse]

OK, I got it to work. In case anyone's interested, I added this line to /etc/fstab:

/dev/hda4	swap		swap	pri=1		0	0

Then saved and rebooted and now:

~$ free -m
             total       used       free     shared    buffers     cached
Mem:          1011        967         44          0         61        384
-/+ buffers/cache:        521        489
Swap:          996         19        976

Thanks Javasnob, you got me going in the right direction.