profile

Linux user Profile Management and Environment Variable¶

User environment customization¶

The operating system provides various commands and initialization files that enable you to customize the behavior and the appearance of your user environment.

You can also customize some of the default resources of the applications you use on your system. Defaults are initiated by the program at startup. When you change the defaults, you must exit and then restart the program for the new defaults take effect.

• System startup files When you log in, the shell defines your user environment after reading the initialization files that you have set up. The characteristics of your user environment are defined by the values given to your environment variables. You maintain this environment until you log out of the system.

• Exporting shell variables (export shell command) A local shell variable is a variable known only to the shell that created it. If you start a new shell, the old shell's variables are unknown to it. If you want the new shells that you open to use the variables from an old shell, export the variables to make them global.

• Changing your system prompt You can change your system prompt.

These files and procedures help the user customize the system environment.

System startup files¶

Customization procedures¶

/etc/profile file¶

The second file that the operating system uses at login time is the /etc/profile file.

The /etc/profile file controls system-wide default variables, such as:

• Export variables
• File creation mask (umask)
• Terminal types
• Mail messages to indicate when new mail has arrived

The system administrator configures the /etc/profile file for all users on the system. Only the system administrator can change this file.

The following is the system default /etc/profile file:

# /etc/profile: system-wide .profile file for the Bourne shell (sh(1))
# and Bourne compatible shells (bash(1), ksh(1), ash(1), ...).

if [ "${PS1-}" ]; then
  if [ "${BASH-}" ] && [ "$BASH" != "/bin/sh" ]; then
    # The file bash.bashrc already sets the default PS1.
    # PS1='\h:\w\$ '
    if [ -f /etc/bash.bashrc ]; then
      . /etc/bash.bashrc
    fi
  else
    if [ "$(id -u)" -eq 0 ]; then
      PS1='# '
    else
      PS1='$ '
    fi
  fi
fi

if [ -d /etc/profile.d ]; then
  for i in /etc/profile.d/*.sh; do
    if [ -r $i ]; then
      . $i
    fi
  done
  unset i
fi

Required Additional configurations¶

We are not changing the default profile but adding additional configuration scripts in /etc/profile.d

We are adding a setting so no core dumps are created and a proper default umask for root and normal users.

nano /etc/profile.d/nocore.sh

# No core files by default
ulimit -c 0 > /dev/null 2>&1

We are adding the default auto logout based on idle time as readonly.

nano /etc/profile.d/auto-logout.sh

# set a 50 min timeout policy for bash shell
TMOUT=3000
readonly TMOUT
export TMOUT

We are setting the default umaks for root and users.

nano /etc/profile.d/umask.sh

# By default, we want this to get set.
# Even for non-interactive, non-login shells.
if [ $UID -gt 99 ] && [ "`id -gn`" = "`id -un`" ]; then
        umask 002
else
        umask 027
fi

nano /etc/bash.bashrc

# By default, we want this to get set.
# Even for non-interactive, non-login shells.
if [ $UID -gt 199 ] && [ "`id -gn`" = "`id -un`" ]; then
        umask 444 
else
        umask 555 
fi

SHELL=/bin/bash

nano /etc/bashrc

nano /etc/csh.cshrc