Most common Linux configuration files

Most common configuration files

aliases: Alias is a fake name you use instead of the actual command

It enables you to replace a word by another string

Example:

command: clear # to clear your screen

alias : cls # doing the same thing

example 2 :

To list all the files in directory in long list format

command: ls –l or ls –ltr (time stamp); or ls –lhA (HUMAN READABLE FOTMAT)

alias: ll

How do we create it?

ll=”ls –ltr”

ll=”ls –lhA”

cls=”clear”

Hence: in simple Alias is a sudo name you a sign to the actual string.

Simple: apache = webserver

bashrc: runs on every interactive shell launch

bashrc: is the overall house configuration file : also known as Bourne

: it is the place for settings up variables, functions and aliases

: must run every time a terminal is open

: it is what loads your customized preferences in the terminal

Bourne SHell. Is your language interpreter (i.e from Spanish to eng)

: Here it is the command line interpreter (lets you talk to the comp)

: Also think of it as the text you type to the computer

crontab or cron.*: Your chamber for configuring all periodic tasks

: ie, tasks that runs automatically in the system

: like backups, sync, updates and patchings

useradd. : Adding user to the system

: i.e. creating your username

Filesystems: Is your directory tree

: Something like this

tree

.

├── admin_tools

│ └── repos-software

│ └── tools

│ └── bin

│ └── qa-linux

│ └── report

│ └── qa.report

ls -R | grep ":$" | sed -e 's/:$//' -e 's/[^-][^\/]*\//--/g' -e 's/^/ /' -e 's/-/|/'

.

|-fwerescripts

|---ansible

|---at_reboot

|---monitoring

|-----onn_off_cronjobs

|-software

|---logs

|---Logs

|-xPlore

|---config

|-----log

Easy way: yum install tree

Run tree command on any directory { tree /etc}

File Ssystem: Is also a way of data storage

: like in files and folders arranged on disk or partitioned

Fstab: Home for mount points.

: cat /etc/fstab ; grep -Rv root /etc/fstab

Accessible filesystems, by reference, are maintained under '/dev/disk'

# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info

****** /boot ext4 defaults 1 2

ftp* : Connectivity to your machine

: Open and closed sections

Group: Config file for fuser groups.

Hosts: home for your server hostname

cat /etc/hosts

127.0.0.1 localhost.localdomain localhost.localdomain localhost4 localhost4.localdomain4 localhost

inittab or inittab - init daemon configuration

: daemon does not use this file, and instead reads its configuration from files in /etc/init

( booting info, restarts, and various requests)

Issue: kernel information

: cat /etc/issue

cat /etc/issue

****************************************************************

THIS SYSTEM IS FOR AUTHORIZED USERS ONLY

There is no right to privacy when using this system.

ld.so.conf: library files.

lilo.conf, silo.conf, aboot.conf: Boot info

: find more in GRUB

logrotate.* : Log cleaning

mail: Mail but in linux OS

modules.conf : Uniques features (drivers)

motd: intext message for admins(announcements , news, etc)

mtab = mount: mounts on your machine (DON’T MESS WITH THESE-MAINLY IN PROD OR YOU HEADING HOME)

cat /etc/mtab

/dev/mapper/vg00-rootvol / ext4 rw 0 0

proc /proc proc rw 0 0

mount

/dev/mapper/vg00-rootvol on / type ext4 (rw)

proc on /proc type proc (rw)

sysfs on /sys type sysfs (rw

nsswitch.conf : Order od hostname resolution from DNS

.pamd :/etc/pam.d : component of pam.conf causes Linux-PAM to ignore /etc/pam.conf config file

: These are the authentication modules

Passwd: User’s passwds stored in /etc/shadow

Useradd, usermod and userdel : anipulating users info

Profile: your shell config ENV

resolv. conf : Your DNS HOME

sendmail.cf : Mail server config

ssh: Secure connection on port 22 to other devices

sysconfig: system config file