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Comment by NoZebra120vClip | Hacker News Reader

What's with the leading underscore? That seems rather unprecedented. Is there some standard that BSD is setting for this?

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All of the system group names that own resources for specific applications have been underscore prefixed for years... like

  ...
  _bgpd:*:75:
  _tcpdump:*:76:
  _dhcp:*:77:
  _mopd:*:78:
  _tftpd:*:79:
  _rbootd:*:80:
  _ppp:*:82:
  _ntp:*:83:
  _ftp:*:84:
  _ospfd:*:85:
  _hostapd:*:86:
  ...

but not the general ones like wheel, sys, daemon, tty, nobody, etc.

Prefix code blocks by two spaces.

Now I wonder why my FreeBSD systems use underscores for some groups, but only a few of them.

  $ grep ^_ /etc/group
  _pflogd:*:64:
  _dhcp:*:65:
  _ypldap:*:160:

Yeah thanks, I edited that like 10 times dealing with escaping the asterisks with backslash, adding the two spaces, removing the escaping, newlines, etc :)

All of those are examples of privilege seperated software imported from OpenBSD, pf and thus pflogd(8), dhclient(8) and yplapd(8).

https://www.openbsd.org/innovations.html

If I recall correctly, all system groups should have a leading underscore for OpenBSD. However, they make exceptions for groups that have been around long before this became their standard.

It's probably to avoid conflicting with potentially existing user-defined groups. The underscore in the C/UNIX world has an intrinsic meaning of "implementation reserved", so it's your fault if the new group conflicts with one you improperly created yourself.

Some other software can think the exact same thing.

This is why I only name users, groups, directories, etc, with UUIDs

"Some other software" that uses/adds users and groups on the system, is not part of the implementation of users and groups in the system.

It's to set system applications' resources aside, and it's more of an OpenBSD thing than a *BSD thing. Once in a blue moon you'll see it in the Linux and general *nix world as well:

  _chrony:x:112:  <-  Debian

It's a majority of the BSDs. NetBSD:

  _pflogd:*:18:
  _rwhod:*:19:
  _proxy:*:21:
  _timedc:*:22:
  _sdpd:*:23:
  _httpd:*:24:
  _mdnsd:*:25:
  _tests:*:26:
  _tcpdump:*:27:
  _tss:*:28:
  _gpio:*:29:
  _rtadvd:*:30:
  _unbound:*:32:
  _nsd:*:33:
  _dhcpcd:*:35:

Debian, in their Policy 4.5.0 said:

"When maintainers choose a new hardcoded or dynamically generated username for packages to use, they should start this username with an underscore."

https://www.debian.org/doc/debian-policy/upgrading-checklist...

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