setting up cgi with nginx

install and run the FastCGI helper

apt -y install fcgiwrap
systemctl list-unit-files | grep fcgi
systemctl status fcgiwrap.socket
ls -lhF /var/run/fcgiwrap.socket
systemctl status fcgiwrap.service

make sure NGINX is ready for that

ls -lhF /etc/nginx/fastcgi_params
#ls -lhF /etc/nginx/fastcgi.conf

make sure your script is executable and test it

vhost=host.example.com

mkdir -p /data/www/$vhost/

cat > /data/www/$vhost/index.cgi <<-EOF9
#!/bin/ksh

cat <<EOF
Content-type: text/html

<p>hello \`host \$REMOTE_ADDR | awk '{print \$NF}'\` (\$REMOTE_ADDR)
EOF
EOF9

chmod +x /data/www/$vhost/index.cgi
ls -lhF /bin/ksh
export REMOTE_ADDR=::1
/data/www/$vhost/index.cgi
unset REMOTE_ADDR

and setup those parms into the vhost server stanza e.g.

vi /etc/nginx/conf.d/$vhost.conf

root /data/www/$server_name;
    index index.cgi maintenance.html;

location ~ (\.cgi|\.py|\.sh|\.pl|\.lua)$ {
    gzip off;
    fastcgi_pass unix:/var/run/fcgiwrap.socket;
    include fastcgi_params;
    fastcgi_param DOCUMENT_ROOT /data/www/$server_name;
    fastcgi_param SCRIPT_FILENAME /data/www/$server_name$fastcgi_script_name;
}

note. be careful with $server_name in the fastcgi parameters: if you do not use a vhost the server name becomes _

note. include fastcgi_params points to conf/fastcgi_params already

ready to go

which nginx
nginx -t
nginx -s reload
#nginx -s reopen

#systemctl restart nginx

additional notes

www-data vs nginx

check what user’s nginx running as

ps auxfw | grep nginx

eventually fix the underlying cgi daemon for that purpose

vi /usr/lib/systemd/system/fcgiwrap.service

User=nginx
Group=nginx

vi /usr/lib/systemd/system/fcgiwrap.socket

SocketUser=nginx
SocketGroup=nginx

systemctl daemon-reload 
systemctl restart fcgiwrap.socket
systemctl restart fcgiwrap.service 
ls -lF /var/run/fcgiwrap.socket