[[!meta title="Boot Sequencing"]] Service scripts are now included in packages that provide system services (e.g. `busybox`). And symbolic links in `/etc/rc.d/` are now more flexibly organized. This current solution currently suffices, and all of the below can be ignored for now. Although, in the future it would be nice to have a more efficient initialization system and some kind of process management. **The rest of this page is kept only for reference and historical purposes.** --- Currently, service init scripts are provided by the monolithic `initscripts` binary package. These init scripts are executed in the lexicographic order of the symbolic links matching `/etc/rc.d/S*` that target them. The names of these symbolic links are currently hardcoded in [the `build` makefile][bf-build] of the `basefiles` source package. This monolithic packaging and hardcoding of link names is a temporary and poor technical solution that doesn't scale with the number and selection of services that can be installed on a system. Init scripts should instead be provided by the packages that provide the relevant system services. The order in which init scripts are executed should be determined by dynamic boot sequencing based on inter-service dependency metadata. This boot sequencing can be done when the system boots or after a new system service is installed. For reference, NetBSD [uses a program called "rcorder"][rcorder-doc] to determine a boot sequence at boot time. Many GNU/Linux distributions follow (to some degree) the Linux Standard Base (LSB) specification, which defines ["Comment Conventions" for dependency metadata][lsb-initscrcomconv] and [a method for installing sequentially-named symbolic links][lsb-initsrcinstrm]. Conforming implementations perform boot sequencing at the time of service installation. Because boot sequencing at boot time can slow down system booting, it is better to perform boot sequencing at install time. Thus, generally speaking, the solution to be adopted in this system is to make packages that provide system services also include the necessary init scripts (installed in `/etc/init.d`), to include inter-service dependency metadata in init scripts, and to use a tool at the time of service package installation to generate sequentially-named symoblic links in `/etc/rc.d`. An obvious boot sequencing tool is ["insserv"][insserv] maintained by Werner Fink and used by Debian and openSUSE. However, this C program (in compliance with the LSB) assumes the use of runlevels. This operating system uses the init daemon of BusyBox, which [doesn't support runlevels][bb-init.c]. Therefore, we'll need to either modify insserv to work without runlevels or write our own tool for installing symbolic links to init scripts. (Either way, the tool should be written in either C or UNIX shell command language, both of which are portable and will be supported by all default installations of the OS.) Additionally, we need to decide how completely we'll conform, if at all, with the LSB in this area. [bf-build]: http://git.os.pehjota.net/pkg/basefiles.git/tree/build?id=0ae24516#n43 [rcorder-doc]: http://www.netbsd.org/docs/guide/en/chap-rc.html#chap-rc-rcorder [lsb-initscrcomconv]: http://refspecs.linuxbase.org/LSB_3.1.0/LSB-Core-generic/LSB-Core-generic/initscrcomconv.html [lsb-initsrcinstrm]: http://refspecs.linuxbase.org/LSB_3.1.0/LSB-Core-generic/LSB-Core-generic/initsrcinstrm.html [insserv]: http://svn.savannah.nongnu.org/viewvc/insserv/trunk/?root=sysvinit [bb-init.c]: http://git.busybox.net/busybox/tree/init/init.c?id=3da46c81#n1221