Init - Replacements For Init

Replacements For Init

Traditionally, one of the major drawbacks of init is that it starts tasks serially, waiting for each to finish loading before moving on to the next. When startup processes end up I/O blocked, this can result in long delays during boot.

Various efforts have been made to replace the traditional init daemons to address this and other design problems, including:

• BootScripts in GoboLinux
• DEMONS, a modification of the init start process by KahelOS, where daemons are started only when the DE (desktop environment) started.
• eINIT, a full replacement of init designed to start processes asynchronously, but with the potential of doing it without shell-scripts
• Initng, a full replacement of init designed to start processes asynchronously
• launchd, a replacement for init introduced in Mac OS X v10.4 (it launches SystemStarter to run old-style 'rc.local' and SystemStarter processes)
• Mudur, an init replacement written in Python and designed to start process asynchronously in use by the Pardus Linux distribution.
• Initscripts, System initialization/bootup scripts for Arch Linux
• runit, a cross-platform full replacement for init with parallel starting of services
• Service Management Facility, a complete full replacement/redesign of init from the ground up in Solaris starting with Solaris 10
• systemd, a full replacement for init with parallel starting of services, reduced shell overhead and other features, used by Fedora 15, OpenSuse 12.1 and Arch Linux.
• SystemStarter, a process spawner started by the BSD-style init in Mac OS X prior to Mac OS X v10.4
• Upstart, a full replacement of init designed to start processes asynchronously initiated by Ubuntu