There are various services that an OS provides. If it is Ubuntu then you may at times want to know which one is enabled and which one is not. The best way to know it is chkconfig.
chkconfig provides a simple command-line tool for maintaining the /etc/rc[0-6].d directory heirarchi by relieving system administrators of the task of directly manipulating the numerous symbolic links in those directories. chkconfig has five distinct functions: adding new services for management, removing servicesfrom management, listing the current startup information for services, changing the startup information for services, and checking the startup state of a particular service.
When chkconfig is run without any options, it displays usage information.
To install chkconfig on Ubuntu
sudo apt-get install chkconfig
To check which services are enabled, just type chkconfig in the terminal and press return. It will list all the services available.
chkconfig can be used with options. More can be learnt from the man pages or here.
