In this project, you export a shell variable to make it globally recognized. To demonst...

In this project, you export a shell variable to make it globally recognized.

To demonstrate the use of the export command:

1. Type cat > testscript and press Enter.

2. Type echo $MY_VAR and press Enter.

3. Type Ctrl+d. You have created a simple shell script named testscript. Its only function is to display the value of the MY_VAR variable.

4. To make the script executable, type chmod ugo+x testscript, and press Enter.

5. Type MY_VAR=2, and press Enter.

6. Type echo $MY_VAR and press Enter to confirm the preceding operation. You see 2 on the screen.

7. Next look at the list of environment variables. Type printenv | more and press Enter.

Look carefully as you scroll through the output of the printenv command. You do not see the MY_VAR variable.

8. Type clear and press Enter to clear the screen.

9. Execute the shell script by typing ./testscript and pressing Enter. The script displays a blank line. This is because it does not have access to the shell variable MY_VAR.

10. Make the variable available to the script by typing export MY_VAR and pressing Enter.

11. Execute the script again by typing ./testscript and pressing Enter. This time, the value 2 appears. (See Figure 6-8 on the next page.)

12. Now look at your list of environment variables by typing printenv | more and pressing Enter. Again, look carefully as you scroll through the list. This time, you see MY_VAR listed.

13. Type clear and press Enter to clear the screen for the next project.