Daca kernelul este motorul oricarei distributii linux atunci cu siguranta init este cheia care il face sa porneasca corect. Fara un program de initiere a proceselor in timpul boot-ului kernelul ar fi inutil. De ceva timp incoace am observat ca sysvinit este inlocuit cu un nou program de administrare a procesului de boot anume systemd. Personal nu am facut cunostiinta cu el sub openSUSE versiunea 11.4 sau Tumbleweed deoarece dezvoltatorii au ales sa il implementeze mai bine pentru 12.1 lucru care mi se pare perfect corect.
Daca am adus in discutie procesul de boot este necesar sa va aduc la cunostiinta ce este init: init (short for initialization) is a program for Unix-based computer operating systems that spawns all other processes. It runs as a daemon and typically has PID 1. The boot loader starts the kernel and the kernel starts init. If one were to delete init without a replacement, the system would encounter a kernel panic on the next reboot. The functionality diverged, in Unix systems such as System III and System V, from the functionality provided by the init in Research Unix and its BSD derivatives. The usage on most Linux distributions is compatible with System V, but some distributions, such as Arch, use a BSD-style and others, such as Gentoo, have their own customized version
Daca init este genul de program care porneste procesele si serviciile aferente in ordine systemd modifica acest aspect: systemd is a replacement for the System V init daemon for Linux. It is intended to provide a better framework for expressing services’ dependencies, allow more work to be done in parallel at system startup, and to reduce shell overhead. The name comes from the Unix convention of suffixing system daemons (background processes) with the letter “d”. In alta ordine de ideei systemd ar trebui sa accelereze procesul de boot prin pornirea in paralel a mai multor procese spre deosebire de predecesorul sau. Personal am fost si sunt multumint de sysvinit, o sa duc dorul comenzilor init 3 pentru oprirea serverului X sau init 5 pentru pornirea acestuia. :) Dintre distributiile linux care au trecut la systemd amintesc aici Fedora precum si Mandriva Linux. Pe viitor distributii linux precum openSUSE versiunea 12.1 vor trece de asemenea la systemd. Alte distributii linux care ofera systemd mai sunt Debian, Arch sau Gentoo.
Tot cautand despre sysvinit si systemd am mai dat peste inca un program de administrare a procesului de boot, anume Upstart: Upstart is an event-based replacement for the /sbin/init daemon which handles starting of tasks and services during boot, stopping them during shutdown and supervising them while the system is running. It was originally developed for the Ubuntu distribution, but is intended to be suitable for deployment in all Linux distributions as a replacement for the venerable System-V init. Upstart este folosit de sisteme de operare precum Maemo 5 al celor de la Nokia, de dispozitive HP si chiar de catre Chrome OS.
