User Environments

The Saigon CTT
User Environments
The Saigon CTT



Objectives
Objectives



Construct different login profiles and user accounts

Define, and modify user environments

Security issues
The Saigon CTT



Login Shells
Login Shells

Shell

an interface between the user and system (kernel).

reads commands from the user and executes appropriate programs

Shell is not implemented as part of OS kernel. The shells is a user-level
program. Administrator can replace the standard shell by another shell.


There are many shells on Linux:
•
Bourne Again Shell (bash) : A superset of the commands of the origin Bourne shell,
also implements features of csh and ksh
•
tcsh : A superset of the commands of the origin C shell
•
Public-domain Korn shell (pdksh):
•
zsh : similar to the ksh with many enhencements
The Saigon CTT



Environment Files
Environment Files

When bash is executed at login time, two initialization
files are executed :

/etc/profile : system-wide initialization file

~/.bash_profile or ~/.bash_login or ~/.profile : personal
initialization file

These files :

Contains system commands


Provide a common environment for all users

Set a user-customized environment

Contain user commands and definitions
The Saigon CTT



Environment Files
Environment Files
SYSTEMWIDE: /etc/profile /etc/bashrc
USER 1
~/.bash_profile
~/.bash_login
~/.profile
~/.bashrc
~/.bash_logout
~/.inputrc
USER 2
~/.bash_profile
~/.bash_login
~/.profile
~/.bashrc
~/.bash_logout
~/.inputrc
USER 3
~/.bash_profile
~/.bash_login
~/.profile

~/.bashrc
~/.bash_logout
~/.inputrc
The Saigon CTT



Environment Files
Environment Files
login
/etc/profile
~/.bash_profile
~/.bash_profile ~/.bash_login
~/.bash_login
~/.profile
~/.bashrc
~/.bash_logout
/etc/bashrc
yes yes
no
no
bash start
logout