Ubuntu: Enable Hibernate (S4) with a Swapfile (plain ext4)
This guide is written for non‑technical users. You will copy/paste a few commands into Terminal.
Easy method (recommended) — Use the one‑click “Enable Hibernate” launcher
If you were provided a folder called hibernate-launcher, you can enable hibernate by double‑clicking:
Enable Hibernate (S4).desktop
You will be asked for an administrator password.
If it does not run:
- Right‑click the file → Allow Launching
- If you don’t see that option: right‑click → Properties → Permissions → enable “Allow executing file as program”
After it completes, reboot.
What this does
- Creates a swapfile at /swapfile (used for hibernate).
- Configures the system so it can resume from hibernation using that swapfile.
- Optionally changes lid close / power button to use Hibernate (S4) instead of Sleep (S3).
Before you start (important)
- Plug in power if possible.
- Save your work and close important apps.
- Security note: hibernation writes the contents of RAM to disk. If your disk is not encrypted, sensitive data may be
recoverable from the swapfile.
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
5) 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.
