minit.8 (4875B)
1 .TH minit 8 2 .SH NAME 3 minit \- a UNIX process no 1 4 .SH SYNOPSIS 5 .B minit 6 7 .SH DESCRIPTION 8 .B minit 9 is a possible first process the kernel starts. 10 11 to use minit as system init, first read available documentation in 12 .I /usr/share/doc/minit 13 and then add the parameter 14 \fIinit=/sbin/minit\fR 15 to your kernel command line. 16 17 .I lilo 18 users need to add it to the \fIappend="something"\fR 19 option in \fI/etc/lilo.conf\fR, 20 21 .I grub 22 users can just append it to their "\fIkernel\fR image options" lines. 23 24 Or, of course, you can just call the binary /sbin/init, which is the 25 default name the kernel starts when no kernel options are given. 26 27 .SH USAGE 28 minit will by default start the minit service called "default". If 29 command line arguments are present, those are started instead of 30 "default". 31 32 It is possible to blacklist a service that is normally started by 33 passing its name with a - in front of it. Example: default depends on 34 init, init depends on loadgfxdriver, loadgfxdriver hangs the kernel in 35 your kernel version so you want to boot without running it. Then you 36 could use grub to pass the additional kernel arguments "default 37 -loadgfxdriver" to minit. Minit would then run default and all its 38 dependencies except loadgfxdriver. 39 40 If the last service exits, minit will terminate. 41 42 In case of catastrophic failure (for example if /etc/minit does not 43 exist), minit will attempt to execute /sbin/sulogin. A careful admin 44 will put some kind of emergency login command and shell there to provide 45 a way to hopefully be able to recover from partially corrupted boot 46 media or botched minit installations. 47 48 .SH SERVICES 49 minit services are defined in /etc/minit/[servicename]/ . When a service 50 is started, minit changes into that directory, and reads the text file 51 "depends". Every line in that file is interpreted as the name of a 52 service and launched recursively like this. Finally, the file "run" is 53 executed. This is usually a symbolic link to a binary. 54 55 If the file "params" exists, each line is passed as a command line 56 argument to the service binary. There is currently no way to pass 57 command line arguments containing newline characters using this 58 mechanism. You would have to make run a shell script to do that. 59 60 All services are launched asynchronously, unless the service directory 61 contains a file called "sync". If that file exists, minit blocks until 62 the service finishes. This is meant for things that need to be 63 completed before anything else can occur in the boot process, for 64 example mounting /usr or /proc. Warning: minit will block when 65 executing sync services, potentially leading to a deadlocked system. 66 minit will also not respond to msvc while waiting for a sync service to 67 commence. 68 69 If a subdirectory called "log" exists, it is interpreted as a minit 70 service, too, and its standard input is connected via a pipe to the 71 standard output of the service. This is meant to be used with tools 72 like multilog from the daemontools, see http://cr.yp.to/daemontools.html 73 74 It is possible to provide data on stdin to a process by putting it into 75 a file (or fifo) called "in" in the service directory. Likewise, if a 76 file or fifo called "out" exists, stdout and stderr of the service will 77 be redirected there. 78 79 If a file called "nice" exists, its contents is interpreted as an 80 integer and passed as argument to nice(2). 81 82 If run is a symbolic link, minit will adjust argv[0] to the name 83 part of it so programs like ps(1) and top(1) display the right name 84 instead of "run". 85 86 If a file called "respawn" exists, minit will restart the service should 87 it ever exit. The default is not to respawn, because in typical 88 scenarios most minit services are actually boot time housekeeping and 89 initialization processes and not actual services that are expected to 90 run for prolonged periods of time. 91 92 If a symbolic link called "root" exists, minit will chdir there before 93 running the service. 94 95 .SH "CONVERTING A DAEMON INTO A SERVICE" 96 97 The concept of minit works around long running service processes that do 98 not terminate. If they do terminate, it is because of some unexpected 99 failure or programming mistake and minit is expected to restart them. 100 101 Unfortunately, most unix services are written as daemons. When run from 102 a shell, they fork into the background and return immediately. In order 103 for minit to be able to detect when those services abort, and to restart 104 them if needed, minit needs to know the PID the service is running 105 under. 106 107 Most services have some way of turning off forking into the background. 108 However, if the particular service does not have a way, pidfilehack can 109 often be used. 110 111 .SH AUTHOR 112 minit was written by Felix von Leitner and can be downloaded from 113 his page at 114 .I http://www.fefe.de/minit/ 115 116 This manpage was written by Erich Schubert <[email protected]> 117 for the Debian GNU/Linux operating system. 118 119 .SH "SEE ALSO" 120 msvc(8), serdo(8), pidfilehack(8)