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simpleinit(8) - init, simpleinit, simpleinit - process control initialization - man 8 simpleinit

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SIMPLEINIT(8)              Linux Programmer's Manual             SIMPLEINIT(8)



NAME
       simpleinit - process control initialization

SYNOPSIS
       init [ single ] [ script ]

DESCRIPTION
       init  is  invoked  as the last step in(1,8) the Linux boot sequence.  If the
       single option is used, or if(3,n) the file(1,n) /etc/singleboot exists, then sin-
       gle  user  mode  will  be  entered,  by  starting /bin/sh.  If the file(1,n)
       /etc/securesingle exists, then the root password will  be  required  to
       start  single  user  mode.   If the root password does not exist, or if(3,n)
       /etc/passwd(1,5) does not exist,  the  checking  of  the  password  will  be
       skipped.

       If  the  file(1,n)  /etc/TZ  exists,  then the contents of that file(1,n) will be
       read(2,n,1 builtins), and used to set(7,n,1 builtins) the TZ  environment  variable  for  each  process
       started  by  simpleinit.  This "feature" is only available if(3,n) it's con-
       figured at compile-time. It's not normally needed.

       After single user mode is terminated, the /etc/rc file(1,n) is executed, and
       the information in(1,8) /etc/inittab will be used to start processes. Alter-
       natively, the /etc/inittab file(1,n) may be configured to  run  a  different
       boot script. See below for details.


THE INITTAB FILE
       Because of the number of init programs which are appearing in(1,8) the Linux
       community, the documentation for the /etc/inittab file(1,n), which  is  usu-
       ally found with the inittab(5) man(1,5,7) page, is presented here:

       The format is

              bootprog=file(1,n)

              fileprefix=string(3,n)

              PATH=search path

              INIT_PATH=search path

              ttyline:termcap-entry:getty-command

              finalprog=path

       An example is as follows:

              bootprog     =
              fileprefix   =  /sbin/init.d/
              PATH         =  /usr/sbin:/usr/bin:/sbin:/bin
              INIT_PATH    =  /sbin/init.d

              tty1:linux:/sbin/getty 9600 tty1
              tty2:linux:/sbin/getty 9600 tty2
              tty3:linux:/sbin/getty 9600 tty3
              tty4:linux:/sbin/getty 9600 tty4
              # tty5:linux:/sbin/getty 9600 tty5
              # ttyS1:dumb:/sbin/getty 9600 ttyS1
              # ttyS2:dumb:/sbin/getty -m -t60 2400 ttyS2

              finalprog   = /sbin/rc.xdm

       Lines  beginning  with the # character are treated as comments.  Please
       see documentation for the getty (8) command that you are  using,  since
       there are several of these in(1,8) the Linux community at this time.

       The  bootprog value is appended to the fileprefix value, and the result
       specifies the boot programme  (script)  to  run.  If  unspecified,  the
       default  is  /etc/rc.  If  the  boot programme is a directory, then all
       scripts in(1,8) that directory tree  are  executed,  in(1,8)  parallel.  See  the
       need(8) programme for details on how to elegantly control order of exe-
       cution and manage dependencies.

       The PATH value is assigned to the PATH environment  variable  of  child
       processes (boot scripts).

       The  INIT_PATH  value is used by simpleinit(8) itself to find the loca-
       tion of scripts to run (if(3,n) an absolute path is not given). If unset and
       the boot programme is a directory, that directory is used.  Finally, if(3,n)
       the script cannot be found in(1,8) this path, the  standard  PATH  is  used.
       This  separation  allows  boot scripts to invoke programmes of the same
       name without conflict and without needing to specify absolute paths.

       The finalprog value specifies the path of the programme  to  run  after
       all  getty(8)  instances  are spawned. At bootup, it is passed a single
       argument: "start". At shutdown(2,8), it is called again, this time(1,2,n) with  the
       argument: "stop".

SIGNALS
       simpleinit(8) responds to signals in(1,8) a variety of ways:

       SIGHUP The /etc/inittab configuration file(1,n) will be read(2,n,1 builtins) again.

       SIGTSTP
              This  flips a toggle, which controls whether more processes will
              be spawned.

       SIGINT simpleinit(8) will sync(1,2,8) a few times, and try to start reboot(8).
              Failing  this,  it will execute the system reboot(2) call. Under
              Linux, it is possible to configure the Ctrl-Alt-Del sequence  to
              send(2,n)  a signal(2,7) to the init process instead of rebooting the sys-
              tem (simpleinit(8) does this by default).

       SIGQUIT
              The reboot(8)  programme  is  executed  in(1,8)  place  of  the  sim-
              pleinit(8)  programme.  This allows reboot(8) to cleanly remount
              (read-only) the root filesystem, even if(3,n) the old inode  for  the
              init process was unlinked.

FILES
       /etc/inittab
       /etc/singleboot
       /etc/securesingle
       /etc/TZ
       /etc/passwd(1,5)
       /etc/rc

SEE ALSO
       inittab(5),  ctrlaltdel(8)  reboot(8), termcap(5), getty(8), agetty(8),
       shutdown(2,8)(8), initctl(8)

BUGS
       This program is called simpleinit to distinguish it from the  System  V
       compatible  versions  of init which are starting to appear in(1,8) the Linux
       community.  simpleinit should be linked to,  or  made  identical  with,
       init for correct functionality.

AUTHOR
       Peter Orbaek (poe@daimi.aau.dk)
       Version 1.20, with patches for singleuser mode by Werner Almesberger
       Richard Gooch <rgooch@atnf.csiro.au>
       Dependency support



Linux 0.99                     25 February 2001                  SIMPLEINIT(8)

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