How to Edit the Hosts File on Linux (2026)

On every Linux distribution, the hosts file lives at /etc/hosts. It is one of the oldest configuration files on Unix systems — present since the early days of networked computing. Editing it requires root privileges and a text editor; this guide covers nano (beginner-friendly) and vim (power user), plus DNS cache flush across different Linux setups.

For the cross-platform overview see How to edit the host file on all platforms.

What is /etc/hosts?

/etc/hosts maps hostnames to IP addresses locally, before your system queries external DNS servers. It is checked first in the name resolution order defined in /etc/nsswitch.conf.

Typical default content:

127.0.0.1   localhost
127.0.1.1   myhostname
::1         localhost ip6-localhost ip6-loopback

The 127.0.1.1 entry (hostname mapping) is common on Debian-based systems — do not remove it without understanding your distro's conventions.

Before you edit: back up

Always create a backup before modifying system files:

sudo cp /etc/hosts /etc/hosts.backup

Restore if something goes wrong:

sudo cp /etc/hosts.backup /etc/hosts

Method 1: Edit with nano (recommended for beginners)

nano is pre-installed on most Linux distributions and shows keyboard shortcuts at the bottom of the screen.

Open the file

sudo nano /etc/hosts

Enter your password when prompted.

Add entries

Navigate to the bottom with arrow keys and add lines:

# Local development
127.0.0.1    app.myproject.test
127.0.0.1    api.myproject.test

# IPv6
::1          app.myproject.test

Save and exit

• Ctrl+O — Write Out (save)
• Enter — Confirm filename
• Ctrl+X — Exit nano

Method 2: Edit with vim

vim is available on virtually every Linux system and preferred by developers who live in the terminal.

sudo vim /etc/hosts

Basic workflow:

1. Press G then o — jump to end and open new line below 2. Press i — enter insert mode 3. Type your entries 4. Press Esc — exit insert mode 5. Type :wq and press Enter — write and quit

To exit without saving: Esc, then :q!

Useful vim commands for hosts file management

/searchterm    " search for a domain
dd             " delete current line
u              " undo
:%s/old/new/g  " replace all occurrences

Hosts file syntax on Linux

IP_address    hostname    [aliases...]

Rules:

• At least one space or tab between IP and hostname
• Lines starting with # are comments
• No wildcards
• First match wins on duplicate entries
• IPv4 and IPv6 on separate lines

Full reference: Hosts file syntax guide.

Example well-organized file:

127.0.0.1       localhost
::1             localhost

# === Dev environment ===
127.0.0.1       app.test
127.0.0.1       api.test
::1             app.test

# === Temporary staging (remove 2026-07-01) ===
203.0.113.50    client.com

Flush DNS cache on Linux

After editing /etc/hosts, flush the resolver cache so changes take effect immediately.

systemd-resolved (Ubuntu, Fedora, Debian, Arch with systemd)

sudo systemd-resolve --flush-caches
# Or on newer systemd versions:
sudo resolvectl flush-caches

Check status:

resolvectl status

nscd (Name Service Cache Daemon)

sudo systemctl restart nscd
# Or legacy:
sudo /etc/init.d/nscd restart

dnsmasq

sudo systemctl restart dnsmasq

No cache daemon running

On minimal systems without a cache daemon, changes to /etc/hosts take effect immediately — no flush needed. Verify with getent hosts.

For Ubuntu-specific systemd-resolved details see Edit hosts file on Ubuntu.

Verify your entries

ping

ping -c 3 app.test

Expected:

PING app.test (127.0.0.1) 56(84) bytes of data.

getent (more reliable than ping)

getent hosts app.test

Expected:

127.0.0.1       app.test

dig (shows full resolution path)

dig app.test

Look for the ANSWER section showing your configured IP.

Common problems on Linux

Permission denied

[ Error writing /etc/hosts: Permission denied ]

Fix: Use sudo. See Edit as administrator.

Changes not taking effect

1. Flush DNS cache (see above) 2. Check /etc/nsswitch.conf — hosts: files dns means hosts file is checked first 3. If using systemd-resolved, verify with resolvectl query domain.test 4. Clear browser DNS cache separately

File is immutable (cannot save even with sudo)

Some hardened systems set the immutable flag:

lsattr /etc/hosts
# If you see ----i--------:
sudo chattr -i /etc/hosts
# Edit, then optionally restore:
sudo chattr +i /etc/hosts

Docker containers ignore host /etc/hosts

Docker containers have their own /etc/hosts. Use --add-host when running containers:

docker run --add-host app.test:127.0.0.1 myimage

SELinux blocking edits (RHEL, Fedora)

sudo ausearch -m avc -ts recent
# If SELinux denied the write, check audit logs and adjust policy if needed

Distribution notes

Automation and scripting

Append an entry from a script:

echo "127.0.0.1    newsite.test" | sudo tee -a /etc/hosts

Remove an entry:

sudo sed -i '/newsite.test/d' /etc/hosts

Idempotent add (only if not present):

grep -q 'newsite.test' /etc/hosts || echo "127.0.0.1    newsite.test" | sudo tee -a /etc/hosts

NetworkManager and desktop Linux

On desktop distributions using NetworkManager (Ubuntu GNOME, Fedora Workstation), DNS settings in the GUI do not replace /etc/hosts — they configure upstream resolvers for domains not listed locally. Your hosts entries remain authoritative for matching hostnames.

If you use nmcli to manage connections, hosts file behavior is unchanged:

nmcli connection show
# hosts file entries still take priority for listed domains

Container and Kubernetes development

Linux developers running minikube, kind, or k3s often combine hosts file entries with cluster ingress:

127.0.0.1    app.local
127.0.0.1    api.local

Point these to localhost where your ingress controller listens (often port 80/443 on the host). The hosts file bridges friendly domain names to the local cluster entry point without requiring a real DNS server in your homelab.

Flatpak and Snap considerations

Some sandboxed applications on Linux use confined network namespaces. Most respect the system /etc/hosts, but if a Snap app ignores your entry, check whether it uses network: host mode or an internal DNS configuration. Testing with getent hosts from the same user session as the app helps isolate sandbox vs resolver issues.

Headless servers and SSH-only access

On Linux servers without a desktop environment, editing hosts is the same sudo nano /etc/hosts workflow over SSH. There is no DNS cache daemon on many minimal server installs — changes often take effect immediately. Verify with getent hosts rather than ping if ICMP is blocked by firewall rules (common on cloud VPS instances).

Best practices for Linux developers

• Use .test TLD for local domains (RFC 2606 reserved)
• Comment and date temporary entries
• Keep /etc/hosts.backup in version control for team projects (not the live file)
• Prefer getent hosts over ping for verification (ping may be blocked by firewall)
• Flush cache after every edit — add to your dev startup scripts

Related guides

• Main guide — all platforms
• Ubuntu-specific guide
• Administrator rights
• Block a website
• Complete reference
• Safety guide

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*Last tested: Ubuntu 24.04 LTS, Fedora 40 — June 2026.*