============================================================================== Finit | Fast Init Replacement ============================================================================== Finit is an extremely fast /sbin/init replacement focusing on small and embedded GNU/Linux systems. It is the continuation of the original finit by `Claudio Matsuoka`_ which was reverse engineered from syscalls of the EeePC fastinit_ daemon -- gaps filled with frog DNA ... This modern finit has extensions for service monitoring, multiple TTYs, one-shot tasks, runlevels and plugins for I/O monitoring, service callbacks and various hooks to extend and adapt it to your needs. Finit restores the raw performance of your system and gives you full control of the ``main()`` loop of ``/sbin/init``! Features -------- **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? * Task/Run callbacks — a one-shot command, should it run in sequence? * 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. /etc/finit.conf --------------- Contrary to most script based init alternatives (`SysV init`_, upstart_, OpenRC_ and the likes) finit instead reads its configuration from ``/etc/finit.conf``. Below is a brief list, see the source code for the full list: check Run fsck on a file system before mounting it module Load a kernel module, with optional arguments network Script or program to bringup networking, with optional arguments runlevel N N is the runlevel number 1-9, where 6 is reserved for reboot run [RUN_LVLS] /path/to/cmd ARGS -- Optional description One-shot command to run in sequence when entering a runlevel, with optional arguments and description. This command is guaranteed to be completed before running the next command. task [RUN_LVLS] /path/to/cmd ARGS -- Optional description One-shot like 'run', but starts in parallel with the next command service [RUN_LVLS] /path/to/daemon ARGS -- Optional description Service, or daemon, to be monitored and automatically restarted if it exits prematurely. Please note that you often need to provide a --foreground or --no-background argument to most daemons to prevent them from forking off to the background. runparts Call run-parts(8) on a directory other than the default /etc/finit.d tty [RUN_LVLS] DEV Run getty on the listed TTY device, in the given runlevels console DEV Some embedded systems have a dedicated console port. This command tells finit to not start getty, but instead print a friendly message and wait for the user to activate the console with a keypress before starting getty. 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! /etc/finit.d ------------ 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, if it exists. Similar to how the ``/ec/rc.local`` file works in most other inits, only finit runs a directory of scripts. This replaces the earlier support for a ``/usr/sbin/services.sh`` script in the original finit_. Runlevels --------- Support for runlevels_ is included in Finit from v1.8. By default all services, tasks, run commands and TTYs listed without a set of runlevels get a default set [234] assigned. The default runlevel after boot is 2. To specify an allowed set of runlevels for a service, run command, task, or tty, add [NNN] to it in finit.conf, like this:: run [S] /etc/init.d/acpid start -- Starting ACPI Daemon task [S] /etc/init.d/kbd start -- Preparing console service [S12345] /sbin/klogd -n -x -- Kernel log daemon tty [12345] /dev/tty1 tty [2] /dev/tty2 tty [2] /dev/tty3 tty [2] /dev/tty4 tty [2] /dev/tty5 tty [2] /dev/tty6 In this example acpid is started once at bootstrap using a conventional SysV init script. Here the run command was used, meaning the following task command is not run until the init script has fully completed. Tasks and services are started in parallell, while run commands are run in the order listed and subsequent commands are not started until a run command has completed. Existing finit.conf files that lack runlevel setting will get a default runlevel assigned, [234]. Switching between runlevels can be done by calling init with a single argument, e.g., 'init 5' switches to runlevel 5. Rebooting and Halting --------------------- Finit handles SIGUSR1 and SIGUSR2 for reboot and halt, and listens to ``/dev/initctl`` so standard Linux reboot and halt commands should also work. Building -------- 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. Running ------- 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 Debugging --------- 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 Contact ------- 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 .. _`Claudio Matsuoka`: http://helllabs.org/finit/ .. _fastinit: http://wiki.eeeuser.com/boot_process:the_boot_process .. _`SysV init`: http://savannah.nongnu.org/projects/sysvinit .. _upstart: http://upstart.ubuntu.com/ .. _runlevels: http://en.wikipedia.org/wiki/Runlevel .. _openrc: http://www.gentoo.org/proj/en/base/openrc/ .. _`finit-1.3.tar.xz`: ftp://troglobit.com/finit/finit-1.3.tar.xz