How to Free Up Disk Space on Linux

A full disk can bring a Linux system to its knees — package installs fail, logs stop rotating, and databases crash. Before you reach for a bigger drive, there's usually several gigabytes recoverable in minutes. This guide covers the most effective targets: package caches, old kernels, systemd journal bloat, large files, and orphaned packages.

Find What's Actually Using Space

Don't guess — measure first. The classic tool is du, but ncdu (NCurses Disk Usage) gives you an interactive view that's much faster to navigate.

Install ncdu

# Debian / Ubuntu
sudo apt install ncdu

# Fedora / RHEL family
sudo dnf install ncdu

# Arch
sudo pacman -S ncdu

Scan your filesystem

# Scan from root, skip other filesystems (NFS, tmpfs, etc.)
sudo ncdu -x /

Use the arrow keys to drill down and press d to delete a selected item directly. Press ? for help. Focus your attention on /var, /home, and /usr — those are the usual culprits.

Quick du one-liners

# Top 20 largest directories under /
sudo du -ahx / 2>/dev/null | sort -rh | head -20

# Size of each top-level directory
sudo du -hx --max-depth=1 / 2>/dev/null | sort -rh

Clean Package Caches

Every package manager caches downloaded archives. On an active system, this cache can easily exceed 2–5 GB.

apt (Debian / Ubuntu)

# Show how much the cache holds
sudo du -sh /var/cache/apt/archives/

# Remove cached packages that are no longer installable (safe)
sudo apt autoclean

# Remove ALL cached packages (frees more space; packages re-downloaded if needed)
sudo apt clean

dnf (Fedora / RHEL / Rocky)

# Show cache size
sudo du -sh /var/cache/dnf/

# Remove all cached data
sudo dnf clean all

pacman (Arch)

# Remove all cached package versions except the currently installed one
sudo paccache -r

# Remove ALL cached packages (more aggressive)
sudo pacman -Scc

paccache is part of the pacman-contrib package. Keeping one or two old versions in cache is useful if a package update breaks something, so paccache -r (keeps last 3) is a sensible default.

Remove Old Kernels

Every kernel update installs a new kernel and leaves the old one in place as a fallback. After a few updates you can accumulate 500 MB or more in /boot and /lib/modules. Keep at least one previous kernel before removing anything.

Debian / Ubuntu

# List installed kernels
dpkg --list | grep linux-image

# autoremove handles old kernels automatically on Ubuntu/Debian
sudo apt autoremove --purge

On Ubuntu, apt autoremove is usually enough — it marks kernels no longer needed as auto-removable after a new one is installed. Always confirm the list before accepting.

Fedora / RHEL / Rocky

# DNF keeps 3 kernels by default; reduce to 2
sudo dnf remove $(dnf repoquery --installonly --latest-limit=-2 -q)

# Or set the limit permanently in dnf.conf
echo 'installonly_limit=2' | sudo tee -a /etc/dnf/dnf.conf

Arch

Arch only installs a single kernel package at a time, so old kernels aren't normally left behind. If you use a custom or LTS kernel alongside the default, remove whichever you don't need with sudo pacman -R linux-lts (or the appropriate package name).

Trim systemd Journal Logs

By default, journald caps logs at 10% of the filesystem or 4 GB, whichever is smaller — but on systems that have been running a while, the journal can still consume over a gigabyte. Check and trim it:

# Check current journal disk usage
journalctl --disk-usage

# Delete logs older than 2 weeks
sudo journalctl --vacuum-time=2weeks

# Or cap the journal to 500 MB total
sudo journalctl --vacuum-size=500M

To make the size cap permanent, edit /etc/systemd/journald.conf:

sudo systemctl edit --force systemd-journald

Or directly set the option:

sudo sed -i 's/^#SystemMaxUse=.*/SystemMaxUse=500M/' /etc/systemd/journald.conf
sudo systemctl restart systemd-journald

Remove Orphaned Packages and Unused Dependencies

Debian / Ubuntu

sudo apt autoremove --purge

Fedora / RHEL / Rocky

sudo dnf autoremove

Arch

# List orphans (installed as deps but no longer needed)
sudo pacman -Qdtq

# Remove them all
sudo pacman -Rns $(pacman -Qdtq)

Be careful with the Arch command: review the list before confirming. Occasionally a package shows as orphaned but is something you actually want.

Clean Up /tmp and Application Caches

Temporary files

On systemd systems, /tmp is often a tmpfs (RAM-based) and cleared on reboot. /var/tmp persists across reboots and can accumulate data:

sudo du -sh /var/tmp
sudo rm -rf /var/tmp/*

User application caches

# See what your own home cache looks like
du -sh ~/.cache/*  | sort -rh | head -15

# Browsers, Electron apps, and Flatpaks are frequent offenders
du -sh ~/.var/app/*/cache/ 2>/dev/null | sort -rh

You can safely delete most contents of ~/.cache — applications rebuild their caches on next run. Do not blindly delete the entire directory; some apps store recoverable session data there.

Flatpak (if used)

# Remove unused Flatpak runtimes
flatpak uninstall --unused

Verify the Results

# Overall filesystem usage
df -h

# Check /boot specifically (important after removing kernels)
df -h /boot

A realistic cleanup on an older desktop or server typically recovers 2–10 GB. Output will vary by system, but you should see the Use% column drop noticeably on the relevant partition.

Troubleshooting

df shows disk nearly full but du totals don't add up

A running process can hold an open file descriptor to a deleted file, keeping the space allocated until the process closes or restarts. Find the culprit:

sudo lsof +L1 | grep deleted

Restart or kill the listed process (often a log daemon or database) to release the space immediately.

/boot is full but autoremove didn't help

On some Ubuntu systems with a separate small /boot partition, the autoremove logic occasionally misses old kernel packages. List and remove manually:

dpkg --list | grep -E 'linux-(image|headers|modules)' | awk '{print $2}'
# Then: sudo apt purge 

Never remove the kernel version currently running. Check the running kernel with uname -r first.

Snap packages (Ubuntu)

Snap keeps two old revisions of every installed snap. Disable this if space is tight:

# List old snap revisions
snap list --all | awk '/disabled/{print $1, $3}'

# Remove all disabled revisions (run a few times if needed)
snap list --all | awk '/disabled/{print $1, $3}' | while read name rev; do
  sudo snap remove "$name" --revision="$rev"
done