Align /etc/hosts File Entries

Formatting Hosts Files

The /etc/hosts file maps IP addresses to hostnames, with fields separated by whitespace (tabs or spaces). As entries accumulate, the file can become messy with inconsistent spacing. Aligning the columns makes it easy to see which IP maps to which hostname.

Before

127.0.0.1 localhost
192.168.1.10 web-server.local
192.168.1.11 db-master.local db-01
192.168.1.12 cache.local redis
10.0.0.1 api-gateway.internal
10.0.0.2 auth-service.internal auth
172.16.0.100 monitoring.corp grafana prometheus

After

127.0.0.1     localhost
192.168.1.10  web-server.local
192.168.1.11  db-master.local         db-01
192.168.1.12  cache.local             redis
10.0.0.1      api-gateway.internal
10.0.0.2      auth-service.internal   auth
172.16.0.100  monitoring.corp         grafana  prometheus

Steps

1. Select Spaces (2+) or Tab as the input delimiter (depending on your file's formatting).
2. Set the output delimiter to Spaces.
3. Enable Trim whitespace.
4. All columns are left-aligned.

Handling Multiple Hostnames

The hosts file allows multiple hostnames per line (aliases). Each additional hostname is treated as an extra column by the aligner, so lines with more aliases will produce more columns. Lines with fewer aliases are padded to maintain alignment.

Comments

Lines starting with # are treated as single-column rows and pass through unchanged. Your existing comments explaining groups of entries will be preserved.

Cross-Platform

This technique works for any hosts-style file:

• Linux/macOS: /etc/hosts
• Windows: C:\Windows\System32\drivers\etc\hosts
• Docker: extra_hosts entries in docker-compose.yml