Welcome to finit!

This is an extremely fast /sbin/init replacement with focus on small embedded GNU/Linux systems. Based on Claudio Matsuoka's original finit with I/O, service and hook plugin extensions. The original was a reimplementation of the EeePC fastinit daemon based on its system calls with gaps filled with frog DNA.

In the world of finit we write C plugins that hook into and extend the main() loop of /sbin/init, this is what gives the system its raw performance and the user full control.

If you chose finit you know what you want, a fast no hassles boot!

Service monitoring

Restarting a service when it exits

Plugins

Extend and modify finit behavior. See examples in plugins/ directory. Plugin capabilities:

• Service callbacks — should the service run/restart/stop?
• Hooks — hook into the boot at predefined points to extend finit
• I/O — listen to external events and control finit behaviour/services

Most extensions and functionality not purely related to what an /sbin/init needs to start a system from the original finit has been reactored into plugins with either hooks or I/O demands.

Contrary to most script based init alternatives (SysV init, upstart, OpenRC and the likes) finit instead reads its configuration from /etc/finit.conf, see the source code for available options.

When running make install no default /etc/finit.conf will be provided since the system requirements differ too much. Try out the Debian 6.0 example /usr/share/doc/finit/finit.conf configuration that is capable of service monitoring SSH, sysklogd, gdm and a console getty!

At the end of the boot, when networking and all services are up, finit calls its built-in run-parts(8) on the /etc/finit.d/ directory, akin to how the /ec/rc.local file works in most other inits, only finit runs a directory of scripts. This replaces the earlier /usr/sbin/services.sh support of the original finit.

Finit handles SIGUSR1 and SIGUSR2 for reboot and halt, and listens to /dev/initctl so standard Linux reboot and halt commands should also work.

The finit build system does not employ the GNU Configure and Build System, instead standard makefiles are used. The user is encouraged to make source code changes, using defines and conditionally building plugins instead to alter the behavior of finit.

The following environment variables are checked by the makefiles and control what is built and where resulting binaries are installed.

ROOTDIR=

Top directory for building complete system, used in pretty printing

VERSION=

Defaults to the currently released version of finit, e.g., 1.3 but can be overridden by packages to add a suffix or completely alter the version.

CFLAGS=

Standard CFLAGS are inherited from the build enviornmant.

CPPFLAGS=

Standard CPPFLAGS are inherited from the build enviornmant.

LDFLAGS=

Standard LDFLAGS are inherited from the build enviornmant.

LDLIBS=

Standard LIBLIBS are inherited from the build enviornmant.

prefix=

Base prefix path for all files, except sbinbdir and sysconfdir. Used in concert with the DESTDIR variable. Defaults to /usr

sbindir=

Path to where resulting binaries should install to. Used in concert with the DESTDIR variable. Defaults to /sbin

sysconfdir=

Path to where finit configuration files should install to. Used in concert with the DESTDIR variable. Defaults to /etc, but is currently unused.

PLUGINS=

List of stock finit plugins to build and install.

plugindir=

Absolute path to where finit should look for dynamically loadable plugins at runtime. At installation prepended by DESTDIR and prefix. Defaults to /lib/finit/plugins

DESTDIR=

Used by packagers and distributions when building a relocatable bundle of files. Alwawys prepended to the prefix destination directory.

Example:

$ tar xfJ finit-1.3.tar.xz
$ PLUGINS="initctl.so hwclock.so" DESTDIR=/tmp/finit/dst \
  make -C finit-1.3/ clean install
make: Entering directory `/home/troglobit/finit-1.3'
  CC      finit.o
  CC      conf.o
  CC      helpers.o
  CC      sig.o
  CC      svc.o
  CC      plugin.o
  CC      strlcpy.o
  LINK    finit
  CC      plugins/initctl.o
  PLUGIN  plugins/initctl.so
  CC      plugins/hwclock.o
  PLUGIN  plugins/hwclock.so
  INSTALL /tmp/finit/dst/sbin/finit
  INSTALL /tmp/finit/dst/lib/finit/plugins/initctl.so
  INSTALL /tmp/finit/dst/lib/finit/plugins/hwclock.so
make: Leaving directory `/home/troglobit/finit-1.3'

In this example the finit-1.3.tar.xz archive is unpacked to the user's home directory, built and installed to a temporary staging directory. The enviroment variables DESTDIR and PLUGINS are changed to suit this particular build.

The default install does not setup finit as the system default /sbin/init, neither does it setup an initial /etc/finit.conf.

It is assumed that users of finit are competent enough to either setup finit as their default /sbin/init or alter their respective Grub, LOADLIN, LILO, U-Boot/Barebox or RedBoot boot loader configuration to give the kernel the following extra command line:

init=/sbin/finit

Add finit_debug, or --debug, to the kernel command line to enable trace messages. A console getty is always started, see the file finit.h for more useful comile-time tweaks:

init=/sbin/finit --debug

Finit is maintained collaborativly at http://github.com/troglobit/finit — please file a bug report, clone it, or send pull requests for bug fixes and proposed extensions, or become a co-maintainer by contacting the main author.

Regards

/Joachim Nilsson <troglobit@gmail.com>