Let's say you have a bunch of sites behind one nginx, and you want to extract all the domains from all the .conf files, one per line. #shell

cd /etc/nginx/sites-enabled
cat * | grep server_name | sed "s/server_name//" | tr -d ";" | cut -f1 -d"#" | xargs | tr " " "\n" | sort | uniq

Explanation

• cat * | grep server_name* → List content from all files in a directory and output the lines containing server_name.
• sed "s/server_name//" → Remove the word "server_name" from those lines.
• tr -d ";" → Delete the semicolon.
• cut -f1 -d"#" → Ignore everything after a # (inline comments).
• xargs | tr " " "\n" → Replace spaces with new lines.
• sort | uniq → Sort lines, get rid of duplicates.

Voila!