getent Command Reference: Databases, Usage & CI Examples

getent queries the system NSS databases like hosts, passwd, and group.

getent reads the Name Service Switch databases the system itself uses, so its host lookups honor /etc/hosts and nsswitch.conf, not just DNS. That makes it the most accurate resolver check in a container.

Common flags and usage

• getent hosts <name>: resolve via NSS (/etc/hosts then DNS)
• getent ahosts <name>: all address families
• getent passwd [user]: user database entries
• getent group [group]: group database entries
• getent services <name>: service/port entries

Example

getent hosts db.internal || echo "name does not resolve via NSS"

In CI

getent hosts reflects how the application will actually resolve a name, including /etc/hosts overrides and container DNS, where dig queries DNS only. Use it to verify a service alias inside a Docker network resolves before connecting.

Key takeaways

• getent queries NSS databases, not just DNS.
• getent hosts mirrors how the app actually resolves a name.
• It honors /etc/hosts and container DNS overrides.

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