On Sun, 14 Jun 1998, Steven A. Reisman wrote:
> Well, severe frustration set in, and I tried increasing numbers of
> backslashes until it worked. The magic number is 6:
>
> if $h_subject matches "\\\\\\$\\\\\\$\\\\\\$"
(1) Because you have put the string in double quotes, \ is interpreted
as an escape when the quoted string is first read in. So the equivalent
is
if $h_subject matches \\\$\\\$\\\$
If you can avoid double quotes in these cases, it helps a bit. :-)
(2) Because each string in a "matches" condition is subject to string
expansion, \ is interpreted as an escape character during expansion. So
after expansion we have
if some-string matches \$\$\$
(3) Then, at last, the regex matching happens, with \ being taken as an
escape for the third time to ensure that the $s are treated as literals.
I will add a few more words to section 19 of the filter document to try
to make it easier to figure out how many backslashes you need, and give
the example of \$.
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