Basic to any system is network access, either to allow others to use its services, or to allow users to access services on other systems. There are two main ways of setting up and controlling networking, the static /ete/network/interfaees file, and the more dynamic Network Manager.
Non-Debian third-party packages often do not provide SysV scripts to start and stop their software's background processes, and you may need to write your own. Even if such scripts are provided, they may need to be modified to follow the Debian standards, particularly ifthey use prepackaged functions available in other distributions that differ from those in Debian.
The update-rc. d utility has already been mentioned, and is one of the primary command line interfaces for managing init scripts. However, there are several other utilities that are essentially a frontend for update -rc . d that make the administrator's job a little easier. The primary ones are bum and sysv-rc-conf.
As mentioned previously, this is now the default as of Debian 7 Wheezy. Itwas introduced in Debian 6 Squeeze, although it could be turned off. It is now always enabled, although provisions are made for legacy ordering (assigning specific numbers to start and stop scripts). Because of this, the administrator no longer needs to determine the order in which the init scripts are run. This is now handled by the insserv utility.
The insservutility should not be called clirectly. The update-reo d
utility provided by Debian, which calls the low-level insserv command,
In Debian, as in nearly all Unix/Unux operating systems, run levels from 0 through 6 are available, defined as follows:
The proper startup and shutdown of services required for a system to function and fulfill its purpose is central to its management. While Unix init scripts (also known as System V or Sys V scripts, due to their origin in Unix System V) have a long history and are in one form or another, common to all Unix and Unux systems, the way in which they are managed, sequenced, enabled, disabled, and the preferred script format often differs somewhat between distributions.
Aside from configuring individual software packages, an administrator is responsible for managing how the various services on his systems are started and stopped, managing network connections, maintaining the filesystem, managing system logs, and configuring the face the system shows to the users.
Although Debian stays close to the upstream software developer's configuration methods, the Debian developers frequently modify configuration file layout to simplify local configuration and upgrades, and often provide additional utilities to ease the administrator's job. Third-party utilities are sometimes available as well, but the administrator should understand that the output of these utilities may not always follow the Debian configuration layout.
Now, with basic software configuration out of the way, it's time to cover more system wide administration issues.
The Apache example should give you a feel for how Debian splits configuration files into smaller, more easily managed files, and provides means to ease various administration tasks, such as activating and deactivation modules. Other software will have different layouts, as well as, different configuration features and utilities, all described in the appropriate documentation.
Once all modifications have been made, and the appropriate sites or modules enabled, it is best to test the configuration for obvious errors. While it is possible to use the init script in /etc/init .d/apache2 for this, the apache2ctl utility is specifically intended for, and better suited for this purpose. There is a configtest command option (detailed in the apache2ctl manual page) which will perform basic checking on all of the included files. It won't catch all errors, but it will catch the majority of them.
