Homework 3

Goals

• Have explored the bash shell.

Assignment

1. [1 point] What is a login shell?
2. [3 points] What happens when bash starts? From which files are commands executed?
3. [3 points] Look at the files listed above and describe the tasks performed in these files.
4. [3 points] ssh
   1. What occurs when a user executes ssh without a command?
   2. How could you use ssh to determine if I am logged into cslab100? Give a command you might type. (The -t option will eliminate an error message)
   3. What environment variables will ssh set on the remote host?
5. [5 points] Read the man page for getenv. Write a program which checks for the following environment variables and prints a greeting.
   • TITLE
   • FIRST_NAME
   • LAST_NAME
   • HONORIFIC
   So if the following were set:

   TITLE="Her Majesty"
   FIRST_NAME="Elizabeth"
   LAST_NAME="the Second"
   HONORIFIC="by the Grace of God of the United Kingdom of Great Britain and Northern Ireland, and of Her other Realms and Territories Queen, Head of the Commonwealth, Defender of the Faith"
       

   Then your program would print

   $ greeting
   Greetings to Her Majesty Elizabeth the Second by the Grace of God of the United Kingdom of Great Britain and Northern Ireland, and of Her other Realms and Territories Queen, Head of the Commonwealth, Defender of the Faith.