Install libnginx-mod-http-subs-filter by entering the following commands in the terminal:
sudo apt update sudo apt install libnginx-mod-http-subs-filter
Substitution filter module for Nginx
Subsitution Nginx module can do both regular expression and fixed string substitutions on response bodies. The module is quite different from Nginx's native Substitution module. It scans the output chains buffer and matches string line by line, just like Apache's mod_substitute.