suse linux interview questions and answers

Suse Interview Questions and Answers http://suse-interview.blogspot.com/

Environment variables can be set in a number of places:

✦ System-wide configuration files such as those located in /etc/profile, /etc/profile.local, and the directory /etc/profile.d on a Linux system. These are system-wide files that are executed to help initialize your working environment each time you log in.

✦ System-wide configuration files such as /etc/bashrc. These are typically executed by a user’s personalized bash configuration file each time that you start a new shell and set system-wide shell configuration variables.

✦ User-specific configuration files such as .bashrc that are read each time you start a new shell.

✦ Within shell scripts for use within those scripts or to be exported back to the command-line environment.

✦ From the command line for your convenience or within shell functions executed by the shell.

Environment variables that you want to make available to all subsequent shells are made available to the parent shell using the export command. For example, suppose that you want to set an environment variable named SAVEME to the name of the current directory so that you can remember it. If the current directory is /home/wvh, you can set the SAVEME environment variable to this directory with the following command:

export SAVEME=/home/wvh

One common task involving environment variables is to add a new directory to the column-separated value of the PATH environment variable so that your shell looks in that directory for executables. For example, suppose that you’ve just installed the popular Linux Firefox browser on your system. Firefox is typically installed in the directory /usr/local/firefox, and the binary program that you actually execute to run the browser is /usr/local/firefox/firefox. You can always execute Firefox by typing the full path of the firefox command, but that’s a bit tedious. A
better solution is to add the directory /usr/local/firefox to the value of your PATH environment variable (generally referred to as “adding it to your path”). You can do this within the current shell by executing the following command:

export PATH=$PATH:/usr/local/firefox

After typing this command, you can execute the firefox command from that shellby simply typing firefox and pressing Return.

you can unset it at any time using the unset command. The unset command removes the environment variable and its associated value from the shell in which you execute it.