This guide is written for non‑technical users. You will copy/paste a few commands into **Terminal**.

## 

## Step 1 — Open Terminal

Try one of these:

* Press **`Ctrl` + `Alt` + `T`**

* Or press the **Windows / Super** key, type **Terminal**, press `Enter`

## Step 2 — Create the swapfile (recommended for 64GB RAM)

The swapfile needs to be large enough to store (roughly) the contents of RAM when hibernating.

As a simple rule:

* Pick a swapfile size that is **at least your RAM size**

* If you are unsure, use **RAM + 25%** (rounded up)

Examples:

* 8GB RAM → 10–12GB swapfile

* 16GB RAM → 20GB swapfile

* 32GB RAM → 40GB swapfile

* 64GB RAM → 72GB swapfile

When you see a password prompt, type your password and press `Enter` (you won’t see the characters as you type — that’s normal).

First, check how much RAM you have:

```
free -h
```

Look at the `Mem:` line (the **total** column).

Copy/paste this whole block into Terminal:

```
set -euo pipefail

# Choose a swapfile size (change this if you have more/less RAM)

# Examples: 12G (8GB RAM), 20G (16GB RAM), 40G (32GB RAM), 72G (64GB RAM)

SWAPSIZE=72G

# Turn off any old swapfile (if present)

sudo swapoff /swap.img 2>/dev/null || true
sudo swapoff /swapfile 2>/dev/null || true

# Remove old /swap.img entry from /etc/fstab (if present)

sudo sed -i.bak '/^[[:space:]]*\/swap\.img[[:space:]]\+none[[:space:]]\+swap[[:space:]]/d' /etc/fstab

# Create /swapfile. This can take a minute or two.

sudo rm -f /swapfile
sudo fallocate -l "$SWAPSIZE" /swapfile

# Lock down permissions (required)

sudo chmod 600 /swapfile

# Format as swap and enable it

sudo mkswap /swapfile
sudo swapon /swapfile

# Make it permanent across reboots

grep -qE '^[[:space:]]*/swapfile[[:space:]]+none[[:space:]]+swap[[:space:]]' /etc/fstab || \
  echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab >/dev/null

# Show result

swapon --show
free -h
```

Expected result:

* `swapon --show` lists `/swapfile` with a size close to what you chose (for example `20G`).

## Step 3 — Configure resume-from-hibernate (the important bit)

Copy/paste this whole block into Terminal:

```
set -euo pipefail

# Find the root filesystem device (where /swapfile lives)

ROOTDEV=$(findmnt -no SOURCE /)
ROOTUUID=$(blkid -s UUID -o value "$ROOTDEV")

# Find the swapfile's physical offset (this is required for swapfile hibernate)

OFFSET=$(sudo filefrag -v /swapfile | awk '$1 ~ /^[0-9]+:$/ {print $4; exit}' | cut -d. -f1)

echo "Root device: $ROOTDEV"
echo "Resume UUID:  $ROOTUUID"
echo "Offset:      $OFFSET"

# Tell initramfs-tools what to resume from

printf "RESUME=UUID=%s\nresume_offset=%s\n" "$ROOTUUID" "$OFFSET" | sudo tee /etc/initramfs-tools/conf.d/resume >/dev/null
sudo update-initramfs -u

# Also add resume arguments to GRUB (more reliable across boots)

sudo sed -i.bak -E 's/(^|[[:space:]])resume=[^[:space:]]+//g; s/(^|[[:space:]])resume_offset=[^[:space:]]+//g' /etc/default/grub
sudo sed -i -E "s/^(GRUB_CMDLINE_LINUX_DEFAULT=\")([^\"]*)\"/\\1\\2 resume=UUID=${ROOTUUID} resume_offset=${OFFSET}\"/" /etc/default/grub
sudo update-grub
```

Note:

* You might see a warning during `update-initramfs` like “no matching swap device is available”. With a **swapfile**, that warning can be harmless (it tries to validate a swap *partition*). The real test is the reboot + resume test below.

## Step 4 — Reboot

Reboot the computer normally.

## Step 5 — Verify it’s configured correctly (after reboot)

Open Terminal again and run:

```
cat /proc/cmdline | tr ' ' '\n' | grep -E '^resume(=|_offset=)'
swapon --show
```

Expected result:

* You see both `resume=UUID=...` and `resume_offset=...`

* `swapon --show` includes `/swapfile`

## Step 6 — Test hibernate

Run:

```
sudo systemctl hibernate
```

If everything is working, the machine should power off, then later boot and **restore your session**.

## If it did not resume (troubleshooting)

After a failed resume (you got a fresh boot), run:

```
journalctl -b -1 | grep -Ei 'hibernate|resume|swsusp|swap|image' || true
dmesg | grep -Ei 'hibernate|resume|swsusp|PM:' || true
```

Common causes:

* The swapfile was recreated or moved (its `resume_offset` changed). Re-run **Step 3**.

* A “defrag” / file-moving tool moved swapfile extents. Avoid defragging `/swapfile`.

## Optional — Make “sleep” actions use Hibernate (S4) by default

This changes what happens when you close the lid or press the power button.

### Option A (graphical) — GNOME via “Dconf Editor”

On many Ubuntu installs (GNOME), the normal **Settings** app does not always show “Hibernate” as a choice. If you want a graphical method, use **Dconf Editor**:

1. Open the app store (**Ubuntu Software** / **App Center**)

2. Install **Dconf Editor**

3. Open **Dconf Editor**

4. Go to:

`org` → `gnome` → `settings-daemon` → `plugins` → `power`

1. Set these to `hibernate`:

* `lid-close-ac-action`

* `lid-close-battery-action`

* `power-button-action`

Optional (also set these to `hibernate` if you want “auto-sleep when inactive” to hibernate):

* `sleep-inactive-ac-type`

* `sleep-inactive-battery-type`

Log out and log back in (or reboot) to be safe.

### Option B (system-wide) — systemd logind.conf

This works even without GNOME and applies system-wide.

Edit logind settings:

```
sudoedit /etc/systemd/logind.conf
```

Set (or uncomment and set) these lines:

```
HandleLidSwitch=hibernate
HandleLidSwitchExternalPower=hibernate
HandleLidSwitchDocked=ignore
HandlePowerKey=hibernate
HandleSuspendKey=hibernate
```

Apply changes:

```
sudo systemctl restart systemd-logind
```

Notes:

* Desktop menus may still show “Sleep” and may still request S3 suspend. The above primarily affects **lid close / keys**.

## Notes

* If `/swapfile` is ever recreated, re-run **Step 3** (offset changes).

* Do not run “defrag” tools on `/swapfile`.