[NTG-context] Error setting up ConTeXt in MacTeX 2020

[Arthur Rosendahl]

  I think I may have found the origin of the error:

On Fri, Sep 18, 2020 at 09:41:23AM +0200, Felix Krause wrote:
>     resolvers       | formats | changing to format path '/var/folders/rj/hfjmjx796q102y4v23vh038c0000gp/T/luatex-cache/context/a86c089b384a3076dc514ba966a1fac9/formats/luatex'
>     resolvers       | formats | unable to change to format path '/var/folders/rj/hfjmjx796q102y4v23vh038c0000gp/T/luatex-cache/context/a86c089b384a3076dc514ba966a1fac9/formats/luatex'

  These messages come from the middle of the file luat-fmt.lua (lines
180 and 183, respectively, on my system) when ConTeXt tries to change
the working directory (that’s what “change” means in this context, just
moving to another directory, as in cd or chdir).  The relevant extract
is

	report_format("changing to format path %a",validformatpath)
	lfs.chdir(validformatpath)
	if dir.current() ~= validformatpath then
	    return fatalerror(startupdir,"unable to change to format path %a",validformatpath)
	end

  In your case validformatpath is a subdirectory of $TMPDIR, under
/var/folders/.  However, if your Mac is anything like mine, /var is
actually a symbolic link to /private/var, so that dir.current() reports
a path starting with /private and the test fails.

  You can work around that by setting TMPDIR to some other value, that
doesn’t start with /var -- and not /tmp either because that’s also a
symbolic link :-)  It should work with a temporary directory in your
home folder.  Can you try that?

	Best,

		Arthur