RHEL Troubleshooting tips

# [Errno 14] yum fails with HTTP/HTTPS Error 404 https://access.redhat.com/articles/1320623

# Solution
rm -fr /var/cache/yum/*
yum clean all 

# Get all selinux properties and their meanings

# Solution
sudo semanage boolean -l 
# Check certain rule eg httpd
sudo semanage boolean -l | grep httpd
# Turn on specific rule, eg. httpd_can_network_connect
setsebool -P httpd_can_network_connect on

# Logs related to each topic.
sudo cat /var/log/messages | grep something

/var/log/messages - all syslog messages except the following
/var/log/secure - security and authentication-related messages and errors
/var/log/maillog - mail server-related messages and errors
/var/log/cron - log files related to periodically executed tasks
/var/log/boot.log - log files related to system startup

# List all loaded services on your system
sudo systemctl list-units --type=service
# OR
sudo systemctl --type=service

# List all active services
sudo systemctl list-units --type=service --state=active
# OR
sudo systemctl --type=service --state=active

# List all running services
sudo systemctl list-units --type=service --state=running 
# OR
sudo systemctl --type=service --state=running