🚀 go-pugleaf

Reading David M. Jones's "TeX Macro Index", I was fascinated by the
entry on Donald E. Knuth's "list.tex" file lister, for which the
typical usage is:

    tex list *.c \\end

Actually,

    tex list file1 file2 ... filen \\end
and
    tex list *.tex \\end

work, too.

But how does it work?  The operative command seems to be:

    \everypar{\grabfile}

However, I don't see how the files following "list" on the command
line are read by TeX and interpreted.

Where in "The TeXbook" does it say that TeX can have more than one
file on the command line?  (I never knew about this, which is what
made me think that "list.tex" might be very interesting.)

Also, how \everypar and \grabfile function?
In particular, what have paragraphs and boxes got to do with reading
files from their names on TeX's command line?

Geoffrey Tobin