[userbinator]

From http://en.wikipedia.org/wiki/TeX#Development

Knuth has kept a very detailed log of all the bugs he has corrected and changes he has made in the program since 1982; as of 2008, the list contains 427 entries, not including the version modification that should be done after his death as the final change in TeX.

The file is called "tex82.bug": http://mirrors.rit.edu/CTAN/systems/knuth/dist/errata/tex82....

Wikipedia is (slightly) out of date since there's 428 currently in the above file, but note that not all of these are actual (functionality-breaking) bugs, just changes; for example, #2 is just a renaming of variables and #425 is an optimisation.

That would be 428 total changes, in a span of a little over 32 years, with the majority of them extremely early in TeX's history - #214 was in 1983, #321 in 1985, #400 in 1991, #420 (a "missing goto") in 2007.

[sillysaurus3]

Thanks! That's one of the coolest changelogs I've ever seen. It's pretty amazing to see 9000 lines represent 32 years of changes.

[jacquesm]

There are a lot of people that would be very happy to receive a check from Knuth for reporting a bug (those checks are rarely if ever cashed, for obvious reasons).

So it's not like people aren't looking for bugs.

[jabagawee]

Donald Knuth no longer writes personal checks for finding errors in his books and code, though he still issues a credit for the correct amount at the (pretty sure it's fictional) Bank of San Serriffe [0]. The page I linked to also mentions that he will try to send legal tender to a bug-finder if she or he really wants it.

[0]: http://www-cs-faculty.stanford.edu/~uno/news08.html