02-16-2008
First s == S; init accepts either upper or lower case s. The meaning of s is built into the init program itself. If init comes up in level s, /etc/inittab is ignored. If init had been in a numeric run level, init will transition down to a point where /etc/inittab is ignored. This is the original and official single user mode. It is the only mode that works if /etc/inittab is missing. While init is in level S, init will ignore requests to reread /etc/inittab. In level S, init would originally connect a shell to the system console so that commands can be entered. Some versions of init, including Sun's, have a change to connect the login program to the console. This change makes the system more secure, but now booting up to single user requires /etc/passwd and /etc/shadow. Some versions of init can do either behavior depending on the security level of the OS. But all of this is built in to init and cannot be changed by modifying /etc/inittab.
The numeric run levels are under the control of the author of /etc/inittab. Sun uses:
0 = firmware mode...OS will die and you get the "ok" prompt
1 = "administrative" mode, Sun's replacement for single user mode with a very few things running
2 = multi-user mode, a lot of stuff running and people can sign on
3 = makes local resources available to other systems
4 = not used
5 = power down the system
6 = reboot the system
So "init 0" is very different... no OS at all will be running. Level s and Level S are different names for the same thing. Level S and 1 are very close in concept. The difference is that a few things will be running in level 1 and level 1 requires a good /etc/inittab.
Also Sun and everyone else cheat a little bit. If you are in a high level and enter level S, you do not really go all the way down to a "true" level S. They will leave a few things running. This leads the system admin's rule that a "true" level S is achieved only by rebooting and coming up directly to level S. This is partially because of intent and partially because some stuff just will not die.
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JMKMF(1) General Commands Manual JMKMF(1)
NAME
jmkmf - runs jmake with the correct options
SYNOPSIS
jmkmf [ top-level dir [ current dir ] ]
DESCRIPTION
Jmkmf is a wrapper which calls jmake with the correct options, defining the symbols TOPDIR (location of the top-level directory) and CURDIR
(current directory). The generated Makefile.SH is then ran through /bin/sh to produce a Makefile.
Jmkmf is useful when you generate a makefile for the first time.
When ran without arguments, jmkmf will scan the directories upwards, looking for a .package file marking the top of your sources. It will
then derive the top-level directory and the name of the current directory by itself.
Once you have a Makefile.SH generated by jmake, and have run Configure already, you can use make Makefile.SH to build the Makefile.SH again
and make Makefile to run the Makefile.SH through /bin/sh. To use the recursive commands, you have to append an 's' at the end of the name
as in make Makefiles.SH and make Makefiles.
AUTHOR
Raphael Manfredi <ram@hptnos02.grenoble.hp.com>
FILES
Jmakefile High level description of makefile
The file marking the top of your package tree
SEE ALSO
jmake(1), packinit(1).
ram JMKMF(1)