None shall pass: the `nologin` program

This meetup concentrates on the common and simple commands; this time: nologin.


The nologin command is a shell used for user accounts that should never have login access, such as nobody or bin. We will start with the simpler BSD implementations: NetBSD, OpenBSD, and FreeBSD. Afterward we'll compare the more complex System V-esque implementations: Illumos/OpenSolaris and Julianne Haugh's Shadow (as used on many Linuxes and now maintaed by Marek Michalkiewicz).


With the many different authors and distinct cultures we will be sure to have much to discuss and compare. Some things to think about: How does the simplicity of the BSD implementations compare to the simplicity of the OpenSolaris implementation? Why does this program exist, and how does it differ from /bin/false? There is no POSIX standard for nologin; why not, and what would it look like? Why is this part of the Shadow suite?


Just in case you don't have five copies of nologin.c sitting on your hard drive, you can find most online:


FreeBSD:


http://svnweb.freebsd.org/base/head/usr.sbin/nologin/nologin.c?revision=139685&view=markup


NetBSD:


http://cvsweb.netbsd.org/bsdweb.cgi/src/sbin/nologin/nologin.sh?rev=1.5&content-type=text/plain


OpenBSD:


http://www.openbsd.org/cgi-bin/cvsweb/~checkout~/src/sbin/nologin/nologin.c?rev=1.5


OpenSolaris (Illumos):


https://github.com/illumos/illumos-gate/blob/694c35faa87b858ecdadfe4fc592615f4eefbb07/usr/src/cmd/login/login.c#L1134-L1152


Shadow (tarball):


http://cdn.debian.net/debian/pool/main/s/shadow//shadow_4.1.5.1.orig.tar.gz


This should all take about three hours. Food and drinks will be provided by thoughtbot.


About us:


This is a reading group for code. Our focus is the classics and tools we use every day. The inspiration is the shared metaphors and expressions we have in natural language due to common books (e.g.  Hitchhiker's Guide to the Galaxy, Romeo and Juliet) and movies (e.g.  Hackers, A Christmas Carol).

Join or login to comment.

  • Jerker K.

    I can only agree with the previous comments. Great fun and interesting discussions.

    April 24

  • Niklas S.

    Great fun as always! Thanks, Mike!

    April 24

  • Fredrik H.

    A great discussion, as always. Thanks Mike for arranging!

    April 23

  • Zeke V.

    Can't go. Snif :~(

    April 23

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