Shell Environment Configuration Lab

1. Work With Login and Non-Login Shells

In this lab, you apply changes to the scripts used to establish the initial shell environment for log in and non-login shells.

  1. Reset your server1.example.com system. After the reset completes, log in as the student user.

  2. Change the student user’s PS1 environment variable to [\u@\h \t \w]$.

    1. Since this is an environment variable, and it should affect only student, edit ~/.bash_profile.

      [student@server1 ~]$ vi ~/.bash_profile

    2. Add an entry for the PS1 variable, setting it to [\u@\h \t \w]$.

       ...
# User specific environment and startup programs

PATH=$PATH:$HOME/.local/bin:$HOME/bin
PS1='[\u@\h \t \w]$ '

export PATH PS1

  3. Set aliases for the student user so that when the rm, cp, or mv commands are used, they are automatically called with the -i option.

    1. Edit the student's ~/.bashrc configuration file.

      [student@server1 ~]$ vi ~/.bashrc

    2. Add aliases for the commands into the file.

       ...
# User specific aliases and functions

alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'

  4. You decided that users on server1.example.com need an application to help them divine the future. Add a function called 8ball, available to all users, that selects a random number between zero and three. Based on the random value, the function should present a message to help them make a decision about the future.

    1. Edit the /etc/bashrc file as root.

      [student@server1 ~]$ su
[root@server1 ~]# vi /etc/bashrc

    2. At the bottom of the file, add the 8ball function.

       ...
8ball () {
  echo "Shaking ..."
  echo
  sleep 3
  value="$[ $RANDOM % 3 ]"
  case $value in
    0) echo "All signs point to yes." ;;
    1) echo "The answer is no." ;;
    2) echo "Ask again later." ;;
    3) echo "Outlook hazy." ;;
  esac
  echo
}

  5. Use an ssh session to create a login shell to verify that the environment changes are effective.

    [root@server1 ~]# exit
[student@server1 ~]$ ssh student@localhost
student@localhost's password: r3dh@t1!
[student@server1 00:06:57 ~]$ touch file1
[student@server1 00:06:57 ~]$ rm file1
rm: remove regular empty file ‘file1’? y
[student@server1 00:06:57 ~]$ 8ball
The answer is no.

2. Configure the Shell Environment

In this lab, you make configuration changes to the shell environment for individual users, and all users, on the machine.

Your international co-workers complain that when they log in to the console of server1.example.com, the language on the machine is set incorrectly. You must configure the machine such that when a user logs in with the terminal type of linux, the LANG variable is set to en_US.

The student user requires an additional command in his environment: diskcheck, which runs iostat -d and df -hP --type xfs.

The student user also needs an environment variable JAVA_HOME set to /usr/lib/jvm.

  1. Reset your server1.example.com system.

  2. Detect the terminal type of a shell. If it is xterm, make sure the language is set to en_US.

    1. Edit the /etc/profile file. At the bottom of the file, add a bit of script which checks the TERM variable to see if it is set to xterm. If it is, assign the LANG variable to en_US and export the LANG setting.

      [root@server1 ~]$ vi /etc/profile
      if [ "$TERM" == "xterm" ]
then
  LANG=en_US
  export LANG
fi

    2. To verify the setting works, use SSH to connect to localhost as student. Check the value of the LANG variable.

      [root@server1 ~]# ssh student@localhost
[student@server1 ~]$ echo $LANG
en_US

  3. Add a function to the student user’s environment. The function is called diskcheck, and when called, it displays the output of the iostat -d and df -hP --type xfs commands.

    1. Edit the student user’s ~/.bashrc and add the function definition. Add the new function at the end of the file.

      [student@server1 ~]$ vi ~/.bashrc
      # User specific aliases and functions
diskcheck() {
  iostat -d
  echo
  df -hP --type xfs
}

    2. Source the ~/.bashrc and verify the function.

      [student@server1 ~]$ . ~/.bashrc
[student@server1 ~]$ diskcheck

  4. Set an environment variable, JAVA_HOME, to /usr/lib/jvm for the student user.

    1. Edit the student user’s .bash_profile, and at the bottom of the file, add an entry for JAVA_HOME. Set JAVA_HOME to /usr/lib/jvm. Use the export command to tag the variable to be available for all sub-shells.

      [student@server1 ~]$ vi ~/.bash_profile
      JAVA_HOME=/usr/lib/jvm
export JAVA_HOME

    2. Source the .bash_profile to read the changes into the environment.

      [student@server1 ~]$ . ~/.bash_profile

    3. Ensure the variable is available in sub-shells.

      [student@server1 ~]$ bash
[student@server1 ~]$ echo $JAVA_HOME
/usr/lib/jvm