The top 6 common debugging methods in Linux.
( 1 ) Increase logging verbosity
As usual, in Linux systems we could look out for errors/warnings/info related messages in "/var/log/messages" file. By default only ‘info’ ( information) and above messages gets logged in to this file, so to increase this logging verbosity one could edit the configuration line of "/var/log/messages" in "/etc/rsyslog.conf" file.
Change this line from :
*.info;mail.none;authpriv.none;cron.none /var/log/messages
to
*.debug;mail.none;authpriv.none;cron.none /var/log/messages
After making this change, save and exit the file. Restart the “rsyslogd” service ( 'systemctl restart rsyslog.service' or 'service rsyslog restart' in case of RHEL6.x and older) to make the changes come into effect. NOTE: Keep in mind that this would generate a lot of logs and "/var" may get filled up fast, so after the diagnosis make sure to revert the changes.
