Background processes are very useful to use a single bash session and run multiple programs in it. They can either run in parallel in the background or are stopped and can be resumed later.

Similarly, sending signals to other programs in the background can be used to change the state of the program by making it active again or move a program in to the foreground. In order to do this there exists a program called kill, which does not only kill by signal a kill.

• USE1.1 Command Line Interface

• Understand interrupting or aborting of a program execution using CTRL-C and CTRL-Z.
• Describe the difference between SIGINT and SIGTSTP.
• Demonstrate the use of CTRL-Z in combination with the commands jobs and fg.
• Understand what a Process ID is and how it can be used to identify any programs.
• Demonstrate how the command jobs can display the process id.
• Understand the behaviour of the kill command.
• Demonstrate the kill command and send the signals SIGKILL, SIGINT, SIGTSTP, also via the numbers instead of the names