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There are a tremendous number of files that a system administrator
needs to work with and to be aware of. Most of these files are
in the /etc directory on your UNIX system. You should
be familiar with several of them by now. This brief presentation
will serve as a reminder as well as an introduction to some new ones!
/etc/checklist - holds the list of the file systems to be checked
for consistency by fsck
/etc/checklist
/etc/fstab - holds the list of all the file systems to be mounted
when the system goes into multi-user mode
/etc/fstab
/etc/gettydefs - contains information that is used by the getty
command to set the speed and terminal settings
for a line
/etc/gettydefs
/etc/group - describes each group of users to the system
/etc/group
/etc/inittab - contains instructions for the /etc/init command.
The instructions define the processes that are to be
created or terminated for each initialization state.
Initialization states are called run-levels or run states.
/etc/inittab
/etc/master.d - directory that contains files that define the
/usr/sys/conf - directory that contains files that define the
configuration of hardware devices, software drivers,
system parameters, and aliases
/etc/master.d
/usr/sys/conf
/etc/passwd - holds the information that identifies
every legitimate user to the system
/etc/passwd
/etc/profile - the default profile for all users. This
file holds the instructions that establish the
default working environment for all users
/etc/profile
/etc/rc - multiuser initialization shell-script. Contains the information
used by /etc/init when the system is moved into multi-user state.
/etc/rc0 - the shell script read by /etc/shutdown in single-user mode, and
/etc/rc2 - the shell script executed by /etc/init
on transition to run-level 2 (multi-user state).
/etc/rc
/etc/shutdown - contains a shell script to gracefully shut
down the system in preparation for system
backup or for scheduled downtime
/etc/shutdown
/etc/utmp - contains information on the run-state of the
system. This information is accessed with a
who -a command
/etc/utmp
/etc/wtmp - contains a history of system logins. The owner
and group of this file must be adm, and the
access permission must be 664. Each time login
is run, this file is updated.
/etc/utmp
/usr/adm/sulog - contains a history of switch user (su) command
usage. As a security measure, this file should not be
readable by others. This file should be periodically
truncated to keep its size within a reasonable limit.
/usr/adm/sulog
/usr/adm/cron/log - holds the history of all actions
taken by /etc/cron. This file also needs
to be truncated periodically to keep its
size within a limit.
/usr/adm/cron/log
/usr/lib/spell/spellhist - contains a history of all words that spell
fails to match. Periodically, this file should be reviewed
for words that should be added to the dictionary.
/usr/lib/spell/spellhist
/usr/spool/cron/crontabs - directory that contains crontab files for
adm, root, and sys logins.
NOTE: Other users can establish their own crontabs if their
name appears in /usr/lib/cron/cron.allow, or if it does not
exist in the /usr/lib/cron/cron.deny file!
/usr/spool/cron/crontabs
/usr/news - directory that contains the news files.
The file names are descriptive of the contents
of the files.
/usr/news
And of course there are many other files and directories
that are too numerous to mention in this tutorial, but you
will discover them as a system administrator.