I couldn't find much documentation about it apart from https://lists.freebsd.org/pipermail/freebsd-questions/2007-January/138772.html. Perhaps it's time to adopt the groups(7) manual page from NetBSD: https://man.netbsd.org/groups.7
https://reviews.freebsd.org/D54114
A commit in branch main references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=e09104dfb76a36b65a64bd315bd1520941c4beed commit e09104dfb76a36b65a64bd315bd1520941c4beed Author: Artem Bunichev <tembun@bk.ru> AuthorDate: 2026-04-28 13:48:52 +0000 Commit: Alexander Ziaee <ziaee@FreeBSD.org> CommitDate: 2026-04-28 13:53:39 +0000 groups.7: New manual page of standard group names Import groups(7) from NetBSD, with tweaks for our system. The group list is sorted by GID. All the group names from /usr/src/etc/group are described, except "uucp". The FILES section was added on top of the original manual page. PR: 264966 Relnotes: yes MFC after: 3 days Obtained from: NetBSD Reviewed by: des, ziaee Differential Revision: https://reviews.freebsd.org/D54114 share/man/man5/group.5 | 3 +- share/man/man5/passwd.5 | 3 +- share/man/man7/Makefile | 2 + share/man/man7/groups.7 (new) | 345 ++++++++++++++++++++++++++++++++++++++++++ usr.bin/id/groups.1 | 5 +- usr.bin/id/id.1 | 5 +- usr.bin/newgrp/newgrp.1 | 5 +- usr.sbin/adduser/adduser.8 | 3 +- usr.sbin/chkgrp/chkgrp.8 | 5 +- usr.sbin/chown/chgrp.1 | 3 +- usr.sbin/chown/chown.8 | 3 +- usr.sbin/pw/pw.8 | 3 +- 12 files changed, 371 insertions(+), 14 deletions(-)
A commit in branch main references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=0f91468c040eb2129618e5ac251afc2529edb462 commit 0f91468c040eb2129618e5ac251afc2529edb462 Author: Alexander Ziaee <ziaee@FreeBSD.org> AuthorDate: 2026-04-28 13:56:23 +0000 Commit: Alexander Ziaee <ziaee@FreeBSD.org> CommitDate: 2026-04-28 13:56:49 +0000 intro.7: Reference groups.7 PR: 264966 MFC after: 3 days share/man/man7/intro.7 | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
A commit in branch stable/15 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=ef42bf7126ef3926a0e3d955e118d556825a556e commit ef42bf7126ef3926a0e3d955e118d556825a556e Author: Alexander Ziaee <ziaee@FreeBSD.org> AuthorDate: 2026-04-28 13:56:23 +0000 Commit: Alexander Ziaee <ziaee@FreeBSD.org> CommitDate: 2026-05-01 15:13:01 +0000 intro.7: Reference groups.7 PR: 264966 MFC after: 3 days (cherry picked from commit 0f91468c040eb2129618e5ac251afc2529edb462) share/man/man7/intro.7 | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
A commit in branch stable/15 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=2c4190609c78c532e0a667eba1ffb4b5c98ea532 commit 2c4190609c78c532e0a667eba1ffb4b5c98ea532 Author: Artem Bunichev <tembun@bk.ru> AuthorDate: 2026-04-28 13:48:52 +0000 Commit: Alexander Ziaee <ziaee@FreeBSD.org> CommitDate: 2026-05-01 15:13:01 +0000 groups.7: New manual page of standard group names Import groups(7) from NetBSD, with tweaks for our system. The group list is sorted by GID. All the group names from /usr/src/etc/group are described, except "uucp". The FILES section was added on top of the original manual page. PR: 264966 Relnotes: yes MFC after: 3 days Obtained from: NetBSD Reviewed by: des, ziaee Differential Revision: https://reviews.freebsd.org/D54114 (cherry picked from commit e09104dfb76a36b65a64bd315bd1520941c4beed) share/man/man5/group.5 | 3 +- share/man/man5/passwd.5 | 3 +- share/man/man7/Makefile | 2 + share/man/man7/groups.7 (new) | 345 ++++++++++++++++++++++++++++++++++++++++++ usr.bin/id/groups.1 | 5 +- usr.bin/id/id.1 | 5 +- usr.bin/newgrp/newgrp.1 | 5 +- usr.sbin/adduser/adduser.8 | 3 +- usr.sbin/chkgrp/chkgrp.8 | 5 +- usr.sbin/chown/chgrp.1 | 3 +- usr.sbin/chown/chown.8 | 3 +- usr.sbin/pw/pw.8 | 3 +- 12 files changed, 371 insertions(+), 14 deletions(-)
A commit in branch releng/15.1 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=56fb2f6daa47022c55458b4dcd11c48fdeed8158 commit 56fb2f6daa47022c55458b4dcd11c48fdeed8158 Author: Alexander Ziaee <ziaee@FreeBSD.org> AuthorDate: 2026-04-28 13:56:23 +0000 Commit: Colin Percival <cperciva@FreeBSD.org> CommitDate: 2026-05-28 22:15:15 +0000 intro.7: Reference groups.7 Approved by: re (cperciva) PR: 264966 MFC after: 3 days (cherry picked from commit 0f91468c040eb2129618e5ac251afc2529edb462) (cherry picked from commit ef42bf7126ef3926a0e3d955e118d556825a556e) share/man/man7/intro.7 | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
A commit in branch releng/15.1 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=0ac3db8805525ea47d0b6a485378d2d88df95edc commit 0ac3db8805525ea47d0b6a485378d2d88df95edc Author: Artem Bunichev <tembun@bk.ru> AuthorDate: 2026-04-28 13:48:52 +0000 Commit: Colin Percival <cperciva@FreeBSD.org> CommitDate: 2026-05-28 22:15:13 +0000 groups.7: New manual page of standard group names Import groups(7) from NetBSD, with tweaks for our system. The group list is sorted by GID. All the group names from /usr/src/etc/group are described, except "uucp". The FILES section was added on top of the original manual page. Approved by: re (cperciva) PR: 264966 Relnotes: yes MFC after: 3 days Obtained from: NetBSD Reviewed by: des, ziaee Differential Revision: https://reviews.freebsd.org/D54114 (cherry picked from commit e09104dfb76a36b65a64bd315bd1520941c4beed) (cherry picked from commit 2c4190609c78c532e0a667eba1ffb4b5c98ea532) share/man/man5/group.5 | 3 +- share/man/man5/passwd.5 | 3 +- share/man/man7/Makefile | 2 + share/man/man7/groups.7 (new) | 345 ++++++++++++++++++++++++++++++++++++++++++ usr.bin/id/groups.1 | 5 +- usr.bin/id/id.1 | 5 +- usr.bin/newgrp/newgrp.1 | 5 +- usr.sbin/adduser/adduser.8 | 3 +- usr.sbin/chkgrp/chkgrp.8 | 5 +- usr.sbin/chown/chgrp.1 | 3 +- usr.sbin/chown/chown.8 | 3 +- usr.sbin/pw/pw.8 | 3 +- 12 files changed, 371 insertions(+), 14 deletions(-)