Init#SysV-style

SysVinit is the init system of the Unix operating system System V. A replica of which is used in many Linux distributions as the default init system.

In SysVinit is the process that is first started by the kernel and therefore gets the process ID 1. This first process starts all required system services based on the desired runlevel.

SysVinit always starts the processes in a predetermined sequence and starts a process usually only when the previous one has finished initializing. This makes it in comparison to other ( "parallel" ) init systems very slowly. Conversely, can therefore easily be diagnosed problems.

Alternatives

First UNIX Solaris sat from autumn 2004 on a successor system (Service Management Facility ), which is started by init and then starts services in parallel on the basis of a calculated dependence graphs, and restarts when needed. The init program starts and monitors only the process svc.startd. Since Linux does not have the necessary SMF "Contract File system" has, SMF can not be ported easily to Linux.

Mac OS X has since April 2005 launchd their own alternative.

Many Linux distributions now have init systems that allow the parallel startup of services. In part, this is done as a modification or extension of the " GNU System-V style init", partly in the form of a complete replacement such as upstart in Ubuntu or younger systemd with Fedora and openSUSE.