using proxy with curl
#!/bin/bash
curl \
-x http://proxy-url:port \
--proxy-user 'proxy-username:proxy-password' \
-H 'User-Agent: Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36' \
-L "https://www.example.com" \
-H 'Accept-Encoding: gzip, deflate, br' \
-H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8' \
-H 'Accept-Language: en-US,en;q=0.5' \
-o output.txt \
-vvv