OpenBSD

The MirOS Project   (Compare Project)

License: apache, artistic_gpl, Beerware, bsd_2clause_ish, BSD-3-Clause, bsd, gpl, MirOS, mit, XFree86_Project_Licence_version_1_1, zlib_libpng

NetBSD   (Compare Project)

Mostly written in C

License: BSD-2-Clause-NetBSD

MidnightBSD   (Compare Project)

Mostly written in C

License: BSD-3-Clause, common_development_and_distribution, gpl, MirOS, lgpl

FreeBSD   (Compare Project)

Mostly written in C

License: BSD-2-Clause

Debian   (Compare Project)

Mostly written in C

License: CoreSystemIV, Distributable

Gentoo Linux   (Compare Project)

Mostly written in Ebuild

License: GNU-GPLv2

Openwall GNU/*/Linux   (Compare Project)

License: Multiple_OSI_Approved

PLD Linux   (Compare Project)

License: gpl

PM2   (Compare Project)

Mostly written in C

License: gpl

Hardware Lister (lshw)   (Compare Project)

Mostly written in C++

License: gpl