The Classical Code Reading Group of Stockholm

Name: Know where you stand: the `pwd` program
Start: 2013-11-28T17:30:00Z
Location: The Park

Know where you stand: the `pwd` program

Nov 28, 2013 · 6:30 PM
The Park

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

The pwd command prints your current working directory. We will start with a brisk walk through the Solaris pwd.c, then through the garden of BSD with Open, Net, and Free. After leaving the BSD brotherhood we trek on to the ksh, bash, and zsh builtins before landing in GNU.

With the many different authors and distinct cultures we will be sure to have much to discuss and compare. Some things to think about: The -P flag caused quite a stir; how do various programmers express this? In many cases this program is a wrapper around getcwd(); what complexities did getcwd() ignore that the program had to deal with? Why does this program exist?

The POSIX documentation on pwd:

http://pubs.opengroup.org/onlinepubs/9699919799/utilities/pwd.html

Just in case you don't have eight copies of pwd.c sitting on your hard drive, you can find them online:

GNU Bash:

http://code.adamrisi.com/p/prestryke/source/tree/master/src/bash/bash-4.1/builtins/cd.def

FreeBSD:

http://svnweb.freebsd.org/base/head/bin/pwd/pwd.c?revision=141578&view=co

GNU:

http://git.savannah.gnu.org/cgit/coreutils.git/tree/src/pwd.c

NetBSD:

http://cvsweb.netbsd.org/bsdweb.cgi/~checkout~/src/bin/pwd/pwd.c?rev=1.22

OpenBSD:

http://www.openbsd.org/cgi-bin/cvsweb/~checkout~/src/bin/pwd/pwd.c?rev=1.11;content-type=text%2Fplain

pdksh:

https://github.com/bobertlo/openbsd-pdksh/blob/master/c_ksh.c#L161

OpenSolaris:

https://github.com/illumos/illumos-gate/blob/master/usr/src/cmd/pwd/pwd.c

zsh:

https://github.com/zsh-users/zsh/blob/master/Src/builtin.c#L669

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).

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Zeke V.

Some day we might even be able to do echo, cp, ls, chmod and kill.

0 · December 2, 2013
- Bengt B.
  
  Baby steps! Baby steps :-)
  
  0 · December 2, 2013
Fredrik H.

Just as good as the last time! Really interesting diskussions.

0 · December 2, 2013
Magnus B.

Lookin' forward to this evening!

0 · November 28, 2013
John-Philip J.

I'm on the waitinglist, but I'm wondering how this meetup works. Do we bring laptops to try things? Is this a open discussion area? A presentation by someone?

0 · November 27, 2013
- View all 3 replies
- Mikael M.
  
  You don't need a laptop, although having read the source code that we'll be going through prior to the evening helps.
  
  0 · November 27, 2013
- Mikael M.
  
  We have one guy display the code with a projector, then we analyse it, make remarks about all kinds of things and compare the different versions of the same kind of application.
  
  0 · November 27, 2013
- Mike B.
  
  It is an open discussion. Picture a bookclub or reading group.
  
  0 · November 27, 2013
Jerker K.

I'm so sad that I'm not able to attend :(. The last time was so fun!

0 · October 31, 2013