Erlang JAM (!) files make OpenOffice not print on Tuesdays

Robert Raschke rtrlists@REDACTED
Tue Sep 8 13:49:42 CEST 2009

A bit off topic, but I thought this was quite amusing. Just came across it
in catching up with my comp.risks reading (


>Date: Sun, 16 Aug 2009 11:27:21 +1000
>From: phil colbourn
>Subject: Cannot print on Tuesdays!

Today I came across an interesting bug mentioned on a blog. The problem was
that printing for some people failed occasionally. Later someone noted that
his Wife had been complaining that she couldn't print on Tuesdays!

In reading through the bug report people were initially claiming that it
must be an OpenOffice bug since all other applications printed fine. Others
noted that it comes and goes. One user found a solution: To remove and purge
the system of OpenOffice and re-install (any easy task on Ubuntu). He
reported on a Thursday that this fixed his printing problem.

Two weeks later he reported (on a Tuesday) that his solution did not work
after-all. Nearly 4 months later the Wife of a Ubuntu hacker complained that
OpenOffice would not print on Tuesdays. I can imagine the scenario:

Wife: Steve, the printer will not work on Tuesdays.
Steve: That's the printer's day off - Of course it will not print on
Wife: No, I'm serious! I can not print from OpenOffice on Tuesdays.
Steve: (Unbelieving..) Ok... Show me.
Wife: I can't show you.
Steve: (Rolling eyes..) Why?
Wife: It's Wednesday!
Steve: (Nods. He says slowly...) Right.

The problem seemed to be tracked down to a program called 'file'. This *NIX
utility uses patterns to detect file types. eg. if the file starts with '%!'
followed by 'PS-Adobe-' then it is a PostScript file. It seems that
OpenOffice writes the date to the postscript file. On Tuesdays it takes the
form of %%CreationDate: (Tue MMM D hh:mm:...)

An error in the pattern for an Erlang JAM file meant that 'Tue' in the
PostScript file was being recognised as an Erlang JAM file and so,
presumably, it was not being sent to the printer.

The Erlang JAM file pattern is:
  4 string Tue Jan 22 14:32:44 MET 1991 Erlang JAM file - version 4.2

It should have been
  4 string Tue\ Jan\ 22\ 14:32:44\ MET\ 1991 Erlang JAM file - version 4.2

With the large number of files types that this program attempts to match
(over 1600) it is not surprising that errors are made in the patterns, but
also the order of matching could mean that false positives are common. In
this case, an Erlang JAM file was matched before the PostScript match


Reported as this bug:

Later made a duplicate to this bug:

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