Inconsistent getent group output with empty groups

Package Information

• Package name: musl
• Package version: musl-1.2.5-r0
• Alpine version: 3.20.3
• Alpine architecture: x86_64

Summary

When a group doesn't contain any members, getent group omits the trailing colon in the output, resulting in only three fields instead of the expected four. This behavior differs from systems using glibc, where getent group consistently includes the trailing colon, even for empty groups.

Steps to reproduce

Alpine Linux (musl-utils):

$ getent group test
test:!:1000  <- Missing the last colon

$ getent group root
root:x:0:root <- Colon present when members exist

glibc-based System:
$ getent group test
test:!:1000: <- Colon present even with no members

Impact

This inconsistency causes issues when parsing the output of getent group with tools like Python's jc library, which expect a consistent number of fields.

Note: I opened an issue upstream and they redirected me here.