When I changed website domain, I had a biggest problem is how to replace all domain on numerous web page file. In this time, I can using some command provided by Linux to solve this problem.
Find file in
/usr/local/nginx/html which include string
grep -lr 'fcsys.us' /usr/local/nginx/html/*
Replace all string in single file by vim editor
%: Replace all string in each line.
g: Replace all matched strings.
Replace all string for all files in a directory
sed -i "s/old/new/g" `grep old -rl /usr/local/nginx/html`