Stal was his name too!

Being a C programmer and GNU/LINUX fan, it would be wrong for me not to post this story about Dennis Ritchie that Mark Lieberman has shared:

The Unix culture favored short identifiers in general: programs like ed, cd, ls, cat, cc, sed, su; directory names like bin, lib, etc, dev; userids like dmr, bwk, mvm. Against this background, 14 characters is a long name; and as Brian Kernighan put it in Unix for Beginners (1979), “14 characters … is enough to be descriptive”. In order to have arbitrary-length file names, you’d need to add another layer of indirection to the file-system data structures; and as Richard Gabriel later wrote about the Bell Labs Unix ethos, “All reasonably expected cases should be covered. Completeness can be sacrificed in favor of any other quality. In fact, completeness must be sacrificed whenever implementation simplicity is jeopardized.”

However, Unix escaped from Bell Labs — that’s part of the story of how Dennis Ritchie helped change the world — and folks in Berkeley had looser (or at least different) moral standards. By 1982 or so, the Berkeley flavor of Unix had developed a file system with arbitrary (or at least much longer) possible file names. So one day, someone sent me a tar tape that had been made on a Berkeley system. And because they’d had the bad taste to take extensive advantage of those longer-than-14-character file names,  my attempt to un-tar the tape was a disaster.

Specifically, as I recall, the overlong file names were simply silently truncated; aside from often concealing their identity and purpose, this caused later files with the same initial 14 letters to overwrite earlier ones.

So I went around the corner to discuss this problem with my colleagues in the Unix research department. Someone patiently explained to me why the 14-character limit was, on balance, a Good Thing. Someone else — certainly not Dennis — may even have suggested that tar’s silent truncation of file names was the Right Thing to Do. Some inconclusive theological controversy ensued.

After talking it over with Dennis, I concluded that re-writing the V7 file system would be too much trouble, as well a violation of local cultural norms, but that modifying tar would be both fairly easy and culturally acceptable. So I got the source code, and hacked tar so that when it encountered over-long file names, it mapped them into 14-character versions guaranteed to be unique, at least insofar as 14 alphanumeric characters permitted, and at the end it wrote out a file giving the table of correspondences between the original file names and the new ones.

This allowed me to get at whatever it was that was on that foreign tape, so I was satisfied. I sent the code around by email to some people that I thought might be able to use it, with a brief note explaining what it was good for, and expressing the hope that this solution would be acceptable “even to those stalwart puritans in the unix research department”. Dennis wrote back that it was indeed acceptable, signing his response “Stal”.

And for some time after that, he continued to use that nickname in private email to me.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


%d bloggers like this: