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. The primary areas to be aware of for Debian startup and shutdown scripts include the purpose of run levels, dependency-based sequencing, and utilities available for administering the boot sequence.
