How do I find out if I have a swap partition on my hard drive?

Question

I used the 12.04 live cd to install Ubuntu over my Windows 7 partition and deleted everything so I just have Ubuntu on my laptop. But since during the installer I chose the simple "erase entire disk" option, did the installer create a swap partition or is that something I should've done with the "something else" option? Btw I have 6GB of RAM

Solution 1

Easy, graphical way to check with Disk Utility

1. Open Disk Utility from the Dash:

   

2. In the left column, look for the words "Hard Disk", and click on that:

   

3. In the right column, see if you can find "Swap" as shown. If so, you have swap enabled; you can click on that portion to see details. It will look something like this:

   

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Alternately, open a terminal with Ctrl+Alt+T, and type swapon -s; if you see a line like the below, with statistics, swap is enabled:

Solution 2

In terminal, type:

free -m

If you happen to have swap, you will see how much swap memory you have left.

Solution 3

Use

cat /proc/swaps

In addition to the size, it will tell the type of swap (partition/file). It appears to give exactly the same output as swapon -s (posted here, but apparently deprecated).

Or

cat /etc/fstab

which will not give you the correct info in the (unusual) case of a swap added manually, as per comment by Carlo Wood.

Solution 4

I'd use this method to verify presence of a swap partition

Open a terminal with CTRL + ALT + T and type

    sudo blkid | grep swap  

If you see an entry with TYPE="swap", be sure that, you have a swap partition.

My output is like below: You can see that /dev/sda7 is a swap partition.

/dev/sda7: UUID="4656a2a6-4de0-417b-9d08-c4a5b807f8dd" TYPE="swap" 

The Installer should create a swap partition automatically. And also note that, You may never need a swap partition, unless you use "Hibernation" feature or use many more applications at a time. You can check these interesting question about swap size

I have 16GB RAM. Do I need 32GB swap?

what is SWAP and how large a swap partition should I create?

If it happens that, You did not create a swap partition, check this question for a help

How do I create a swap partition for hibernation?

Solution 5

Do lsblk and check for SWAP near the end.

In simple terms, lsblk | grep SWAP
output:

├─sdb2   8:18   0   7.6G  0 part [SWAP]

If you're not familiar with lsblk, lsblk lists partitions , their mountpoint, their size etc.

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Comments

[luv.preet]

run cat /proc/swaps OR swapon -s, It will list the swap partition and swap file which is being used.

[sancho.s ReinstateMonicaCellio]

@luv.preet - This answer shows that.

[thomasrutter]

swapon -s is the easiest way if you didn't set up the computer so you're not sure where the swap would be located (or if it uses a swap file instead of a swap partition, or swap on a different drive, swap in compressed RAM, etc).

[Takkat]

See also: askubuntu.com/questions/33697/… and (for a swap file in case we can't partition) askubuntu.com/questions/126018/…

[mightypile]

As Anwar Shah mentioned, this can show you whether you have a partition designated as swap, but this doesn't mean you're using it. Doing this to find swap partitions and verifying with idx's suggestion of 'swapon -s' that they match would be a great solution.

[AnotherKiwiGuy]

Can you explain this a little better? Not everyone is familiar with terminal commands. It might benefit others if you explain what this means. For example, what is lsblk, and what does it do? What does the output mean? Things like that :)

[dthor]

swapon -s is now deprecated in favor of swapon --show [source]

[bbodenmiller]

free -mh will make it human readable

[AjayKumarBasuthkar]

with lubuntu 18.04.1, sudo fdisk -l did NOT show swap partition, swapon --show works fine.

[sancho.s ReinstateMonicaCellio]

It appears that cat /proc/swaps is the perennial way of doing this, see answer below.

[Carlo Wood]

The info in /etc/fstab is neither a guarantee nor always available. That file is used to configure a swap during boot and/or running swapon -a, but if you added a swap manually then it won't necessarily be in /etc/fstab.

[sancho.s ReinstateMonicaCellio]

@CarloWood - Good to know. So you say cat /proc/swaps is reliable in those cases that cat /etc/fstab is not?

[Carlo Wood]

Yes - I had an empty /etc/fstab, but /proc/swaps still showed me the swap that I just added manually.

[Alex Meiburg]

This is incorrect, because free -m will only show the presence of swap at all; it won't show whether it's a swap file or swap partition.

[Timo]

/proc/swaps shows nothing, free -m shows swap 0, df shows nothing,'blkid` shows /dev/sda2 lsblk -o name,fstype,size shows swap 5 G /dev/sda2. So I have swap but a hidden one? When I do systemctl hibernate I get Failed to hibernate system via logind: Not enough swap space for hibernation. What can I do? cat /proc/meminfo shows 6 GB of RAM. Is 1 GB of swap space missing?

[Timo]

On debian I had to lsblk -o fstype, size to show swap.

[Timo]

@AnotherKiwiGuy, man lsblk will give you a starting kick in.