The new Knuth TeX has been released in early this month, and its version number is 3.14159265 now. It can be downloaded here.

What's new in this release?

And a further-more question, where can one find the change log of TeX (itself), and will D.E.K. himself summarize the change(s) somewhere?

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    I believe Stack Exchange (ergo Tex) is not an news site. People wondering what a new version brings should read the changelog.
    – Braiam
    Commented Jan 19, 2014 at 18:00
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    @Braiam While that is true, remember that (1) each site has a bit different policies of various stuff, (2) this is much more subtle and specific than asking "what is new in C++11", (3) this information is significantly harder to find than for other stuff, where the "wiki-idea" of StackExchange can come to play. This is not about a specific package inside *TeX, this is about the TeX!
    – yo'
    Commented Jan 19, 2014 at 19:04
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    @tohecz I find more useful teach the user how to catch the fish, so maybe a question about "How I find the change made in the TeX?" would be more productive and relevant, no?
    – Braiam
    Commented Jan 19, 2014 at 21:21
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    @Braiam However, only useful to him, only for 5 minutes. This question is useful to many. The new version of TeX is its 9th version in it's more-than-40-year-long existence. It's not something that happens every day and that would get outdated soon, giving people need to have a similar but different question next week. Very likely the next change in TeX core will be not sooner than in 5 years, and again, it will likely be a minor change like this one. I'd suggest you to settle down here, I'm sure that in some time you'll find out that this question is just fine, and actually very good!
    – yo'
    Commented Jan 19, 2014 at 21:55
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    I don't know what is new, but from the texbook.log I see that D.E.K. uses TeX Live 2009/Debian. Good to know.
    – alfC
    Commented Jan 20, 2014 at 8:15

2 Answers 2


There have been two bug fixes, one in TeX and one in Metafont. If you look into the tarball, you find a subdirectory called errata. In it you find


In the last file there's a resumé of the changes, in the first two you can find the actual corrections.1

The bug fix in TeX is related to the control sequence with empty name.

428​. \endcsname\csname should be followed by space in print_cs, just as all other multiletter control sequences are (found by Oleg Bulatov, 14 Sep 2008)

@x module 262
      begin print_esc("csname"); print_esc("endcsname");
      begin print_esc("csname"); print_esc("endcsname"); print_char(" ");

If one runs the (admittedly bizarre) TeX file

% define the empty control sequence
% define another macro
% show \baz

the output on the terminal is

> \baz=macro:
->\csname\endcsnametext .
l.9 \show\baz

while, with the bug fix, it will be

> \baz=macro:
->\csname\endcsname text.
l.9 \show\baz

as it should. The result of \show applied to the empty control sequence is always represented as \csname\endcsname: the bug produces invalid output, as it can be clearly seen.

The bug fix in Metafont is related to a memory leak:

572​. Memory leak in make_ellipse on symmetric pens that don't have a point on the x-axis (Eberhard Mattes, 03 June 2008)
@x module 536
done1: link(p):=s; beta:=-y_coord(h);
done1: if (link(p)<>null) then free_node(link(p),knot_node_size);
link(p):=s; beta:=-y_coord(h);

Congratulations to Oleg Bulatov and Eberhard Mattes (the creator of emTeX, by the way) for having being awarded the check from DEK.

By the way, there is a bug in the bug list: in the first above reported line it should be


and not


Is this worthy a check? ;-)


1 An article by Knuth in TUGboat was published after I wrote this answer.

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    Hi egreg. Do you know where I can download the latesat version of plain.tex from Knuth's homepage? I can't find it (which I've been abel to before). Commented Jan 19, 2014 at 16:25
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    @SvendTveskæg In the tarball you find plain.tex in the lib subdirectory. There has been no change to it. Only manmac.tex has been slightly modified.
    – egreg
    Commented Jan 19, 2014 at 16:30
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    okay, @egreg, i'll forward that report to dek; it's up to him to decide whether it's worth a check. his summary of changes will be published in the next issue of tugboat. Commented Jan 19, 2014 at 17:08
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    @glglgl The last batch of bug fixes was carried out in 2007. Considering that the bug can manifest itself only in very obscure settings, there was no hurry. In the past there have been urgent fixes besides the planned maintenance.
    – egreg
    Commented Jan 19, 2014 at 20:50
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    For future reference, might also be worth linking to The TeX tuneup of 2014, published in TUGboat, Volume 35 (2014), No. 1. Commented Feb 4, 2018 at 4:50

In the file ./errata/TeX82.bug, you will find what you want:

428. \endcsname\csname should be followed by space in print_cs, just as all
other multiletter control sequences are (found by Oleg Bulatov, 14 Sep 2008)

@x module 262
      begin print_esc("csname"); print_esc("endcsname");
      begin print_esc("csname"); print_esc("endcsname"); print_char(" ");

I don't think this is something that could be called 'new (feature)', however, our TeX has just stepped further to the version pi. Oh, if you've read the message just below, you may not like this 'bad news'. :(

999. The absolutely final change (to be made after my death)
@x module 2
@d banner=='This is TeX, Version 3.14159265' {printed when \TeX\ starts}
@d banner=='This is TeX, Version $\pi$' {printed when \TeX\ starts}
When this change is made, the corresponding line should be changed in
Volume B, and also on page 23 of The TeXbook.
My last will and testament for TeX is that no further changes be made
under any circumstances. Improved systems should not be called simply `TeX';
that name, unqualified, should refer only to the program for which I have
taken personal responsibility.  -- Don Knuth
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    the "bad news" has been there since at least the early 1980s. the request that the exact name "TeX" be used only for knuth's original version has been honored by everyone so far who has created any extensions. in fact, latex these days is based on pdftex, not on the canonical "TeX"; however, all extensions of which i am aware have also tried to make sure that a version of the extended program will pass knuth's "trip" test, to ensure that the program as documented in the texbook remains valid. Commented Jan 19, 2014 at 17:06
  • Thank you Ch'en Meng, but I think the answer from egreg is better, since he/she provides more explanation about the very change. Vote up for your information.
    – Shadow
    Commented Jan 20, 2014 at 1:43

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