Installation guide

system environment. To understand and utilize available functionality, you
should familiarize yourself with the init program and the specific files
and commands associated with the program. Refer to the init
(8) reference
page for a description of the program and its behavior.
Before you make any changes to the system initialization files, you should
examine the default setup, evaluate the needs of your system, and make a
copy of the entire set of default files. Taking precautions is wise when
making changes to system files or to files that alter the working
environment. If you discover that your modifications do not create the
environment that you intended, you can reinstate the default files while
you fix the problems in your customized environment.
The following system files and directories influence system startup and
operation:
/etc/inittab
One of the key initialization files whose entries define run levels and
associated processes and administer terminals. Section 4.1.1 describes
this file.
/etc/securettys
A text file that marks whether a given tty line allows root logins.
Section 4.1.1.7 describes this file.
/sbin/bcheckrc
A system initialization run command script associated with checking
and mounting file systems at startup time. Section 4.1.1.2 describes
this file.
/sbin/init.d
The initialization directory that contains executable files associated
with system startup and the available run levels. Section 4.1.2.1
describes the directory structure and contents.
/sbin/rc
n .d
A set of individual directories that correspond to the various run
levels. Each directory contains linked files that the system acts on
when starting or changing a particular run level. There are three
/sbin/rc
n .d directories available: /sbin/rc0.d, /sbin/rc2.d,
and /sbin/rc3.d. Section 4.1.2.2, Section 4.1.2.3, and Section 4.1.2.4
describe the rc directory structure and contents.
4–2 Customizing the System Environment