Why are user application configuration files saved in the user’s home directory and not under /etc with all the other system-wide configuration files?

Locating Configuration Files
a. Use the ls command to list all the files in the analyst home directory:



[analyst@secOps ~]$ ls –l

total 20

drwxr-xr-x 2 analyst analyst 4096 Sep 26 2014 Desktop

drwx------ 3 analyst analyst 4096 Jul 14 11:28 Downloads

drwxr-xr-x 8 analyst analyst 4096 Jul 25 16:27 lab.support.files

drwxr-xr-x 2 analyst analyst 4096 Mar 3 15:56 second_drive

-rw-r--r-- 1 analyst analyst 254 Aug 16 13:32 space.txt

While a few files are displayed, none of them seem to be configuration files. This is because it is convention to hide home-directory-hosted configuration files by preceding their names with a “.” (dot) character.
b. Use the ls command again but this time add the –a option to also include hidden files in the output:



[analyst@secOps ~]$ ls –la

total 268

drwxr-xr-x 19 analyst analyst 4096 Aug 2 15:43 .

drwxr-xr-x 3 root root 4096 Sep 26 2014 ..

-rw------- 1 analyst analyst 250 May 4 11:42 .atftp_history

-rw------- 1 analyst analyst 13191 Aug 1 09:48 .bash_history

-rw-r--r-- 1 analyst analyst 97 Mar 21 15:31 .bashrc

drwxr-xr-x 4 analyst analyst 4096 Jul 6 10:26 broken_down

drwxr-xr-x 10 analyst analyst 4096 Nov 7 2016 .cache

drwxr-xr-x 12 analyst analyst 4096 Jun 5 11:45 .config

-rw-r--r-- 1 analyst analyst 16384 Apr 12 10:06 .cyberops_topo.py.swp

drwxr-xr-x 2 analyst analyst 4096 Sep 26 2014 Desktop

-rw-r--r-- 1 analyst analyst 43 Sep 27 2014 .dmrc

drwx------ 3 analyst analyst 4096 Jul 14 11:28 Downloads

-rw-r--r-- 1 analyst analyst 72 Sep 26 2014 .fehbg

drwxr-xr-x 5 analyst analyst 4096 Sep 26 2014 .fluxbox

drwx------ 3 analyst analyst 4096 Sep 7 2016 .gnupg

-rw------- 1 analyst analyst 28920 Aug 2 15:01 .ICEauthority

drwxr-xr-x 2 analyst analyst 4096 Sep 26 2014 .idlerc

drwxr-xr-x 3 analyst analyst 4096 Sep 27 2014 .java

drwxr-xr-x 8 analyst analyst 4096 Jul 25 16:27 lab.support.files

-rw------- 1 analyst analyst 290 Jul 6 15:15 .lesshst

drwxr-xr-x 3 analyst analyst 4096 Sep 26 2014 .local

c. Use the cat command to display the contents of the .bashrc file. This file is used to configure user-specific terminal behavior and customization.



[analyst@secOps ~]$ cat .bashrc

export EDITOR=vim

PS1='\[\e[1;32m\][\u@\h \W]\$\[\e[0m\] '

alias ls="ls --color"

alias vi="vim"

Do not worry too much about the syntax of .bashrc at this point. The important thing to notice is that .bashrc contains configuration for the terminal. For example, the line PS1='\[\e[1;32m\][\u@\h \W]\$\[\e[0m\] ' defines the prompt structure of the prompt displayed by the terminal: [username@hostname current_dir] followed by a dollar sign, all in green. A few other configurations include shortcuts to commands such as ls and vi. In this case, every time the user types ls, the shell automatically converts that to ls –color to display a color-coded output for ls (directories in blue, regular files in grey,
executable files in green, etc.) The specific syntax is out of the scope of this course. What is important is understanding that user configurations are conventionally stored as hidden files in the user’s home directory.
d. While configuration files related to user applications are conventionally placed under the user’s home directory, configuration files relating to system-wide services are placed in the /etc directory, by convention. Web services, print services, ftp services, email services are examples of services that affect the entire system and of which configuration files are stored under /etc. Notice that regular users do not have writing access to /etc. This is important as it restricts the ability to change the system-wide service configuration to the root user only.
Use the ls command to list the contents of the /etc directory:



[analyst@secOps ~]$ ls /etc

adjtime           host.conf           mke2fs.conf         rc_maps.cfg

apache-ant        hostname            mkinitcpio.conf     request-key.conf

apparmor.d        hosts               mkinitcpio.d        request-key.d

arch-release      ifplugd             modprobe.d          resolv.conf

avahi             initcpio            modules-load.d      resolvconf.conf

bash.bash_logout  inputrc             motd                rpc

bash.bashrc       iproute2            mtab                rsyslog.conf

binfmt.d          iptables            nanorc              securetty

ca-certificates   issue               netconfig           security

crypttab          java-7-openjdk      netctl              services

dbus-1            java-8-openjdk      netsniff-ng         shadow-

default           kernel              nginx               shadowdepmod.

depmod.d          krb5.conf           nscd.conf           shells

dhcpcd.conf       ld.so.cache         nsswitch.conf       skel

dhcpcd.duid       ld.so.conf          ntp.conf            ssh

dkms              ld.so.conf.d        openldap            ssl

drirc             libnl               openvswitch         sudoers

elasticsearch     libpaper.d          os-release          sudoers.d

environment       lightdm             pacman.conf         sudoers.pacnew

ethertypes        locale.conf         pacman.conf.pacnew  sysctl.d

filebeat          locale.gen          pacman.d            systemd

fonts             locale.gen.pacnew   pam.d               tmpfiles.d

fstab             localtime           pango               trusted-key.key

gai.conf          login.defs          papersize           udev

gemrc             logrotate.conf      passwd              UPower

group             logrotate.d         passwd-             vdpau_wrapper.cfg

group-            logstash            pcmcia              vimrc

group.pacnew      lvm                 pkcs11              webapps

grub.d            machine-id          polkit-1            wgetrc

gshadow           mail.rc             profile             X11

gshadow-          makepkg.conf        profile.d           xdg

gshadow.pacnew    man_db.conf         protocols           xinetd.d

gtk-2.0           mdadm.conf          pulse               yaourtrc

gtk-3.0           mime.types          rc_keymaps

e. Use the cat command to display the contents of the bash_bashrc file:



[analyst@secOps ~]$ cat /etc/bash.bashrc

#

# /etc/bash.bashrc

#

# If not running interactively, don't do anything

[[ $- != *i* ]] && return

PS1='[\u@\h \W]\$ '

case ${TERM} in

xterm*|rxvt*|Eterm|aterm|kterm|gnome*)

PROMPT_COMMAND=${PROMPT_COMMAND:+$PROMPT_COMMAND; }'printf

"\033]0;%s@%s:%s\007" "${USER}" "${HOSTNAME%%.*}" "${PWD/#$HOME/\~}"'

;;

screen)

PROMPT_COMMAND=${PROMPT_COMMAND:+$PROMPT_COMMAND; }'printf

"\033_%s@%s:%s\033\\" "${USER}" "${HOSTNAME%%.*}" "${PWD/#$HOME/\~}"'

;;

esac

[ -r /usr/share/bash-completion/bash_completion ] && . /usr/share/bash-completion/

bash_completion

[analyst@secOps ~]$

The syntax of bash_bashrc is out of scope of this course. This file defines the default behavior of the shell for all users. If a user wants to customize his/her own shell behavior, the default behavior can be overridden by editing the .bashrc file located in the user’s home directory. Because this is a system-wide configuration, the configuration file is placed under /etc, making it editable only by the root user. Therefore, the user will have to log in as root to modify .bashrc.

Regular users do not have permission to write to /etc. Because Linux is a multi-user operating system, placing user-application configuration files under /etc would keep users from being able to customize their applications.