useful DevOps commands

server_side_tidbits.py

# see debain handbook for admins :   https://debian-handbook.info/

# django error: That port is already in use

netstat -lpn | grep: <port_number>
kill -9 <process_id>

# View apache2 errors

cat /var/log/apache2/error.log
#OR
cat /var/log/apache2/<my_custom_file_name>.log

systemctl status apache2.service 

journalctl -xn -l  # -l makes it verbose

# raeving up apache2
sevice apache2 { start | stop | graceful-stop | restart | reload | force-reload | start-htcacheclean | stop-htcacheclean }

# securely  give 'www-data' root privileges

# 1: Create a new group
addgroup <group_name>

# 2: Add 'www-data' to the group
adduser www-data <group_name>

# 3: Change group ownership of the target directory
chown -vR : <group_name>  /path/to/target/dir/

# 4: Grant write permission to the new dir owner
chmod -vR g+w   /path/to/target/dir

# wrap up -- see how apache2 is running
ps aux | grep apache2 | less

# Check the installed apache2 version (debian)
apachectl -V
#OR
apache2 -V


# enable site
a2ensite

# disable site
a2dissite

# enable an apache2 module
a2enmod

# disable an apache2 module
a2dismod

# add this (to 'apache2.conf' or 'httpd.conf') prevent mod_wsgi server timeouts if numpy is installed
# see SO answer: http://stackoverflow.com/questions/40413171/django-webfaction-timeout-when-reading-response-headers-from-daemon-process
WSGIApplicationGroup %{GLOBAL}