Unable to escape $ sign in subs_filter

[omar_h]

Hello,

I am trying to add some code to a page which contains a $ symbol.  However,
I am getting the following error:

nginx: [emerg] invalid variable name

Here is a simple example of the config:

subs_filter 'example' '$';

Is there any way to escape the $ symbol?  The issue occurs even with single
brackets, which normally should take strings as literal without any variable
substitution.  It seems like a bug since this behavior should only occur
with double brackets.

This issue was also discussed in the past, however, the workarounds don't
work in my case
https://forum.nginx.org/read.php?29,243808,243808#msg-243808
https://forum.nginx.org/read.php?2,218536,218536#msg-218536

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,276801,276801#msg-276801