Session 5 Report

[mousavi2003]

Team Name: [FILL HERE]

Student Name of member 1: Seyyedeh Fatemeh Mousavi
Student No. of member 1: 400105252

Student Name of member 2: [FILL HERE]
Student No. of member 2: [FILL HERE]

Student Name of member 3: [FILL HERE]
Student No. of member 3: [FILL HERE]

• Read Session Contents.

Section 5.3.1

• Write the Hello World! program

  • FILL HERE with your source code

• Write the ls to wc program

  • FILL HERE with your source code

• Investigate how to have a bi-direction pipe

  • FILL HERE with your descriptions

Section 5.3.2

• Describe the usecase of different signals:

  1. SIGINT: SIGINT is the signal sent when we press Ctrl+C. The default action is to terminate the process. However, some programs override this action and handle it differently. One common example is the bash interpreter. When we press Ctrl+C it doesn't quit, instead, it prints a new and empty prompt line.
  2. SIGHUP: SIGHUP ("signal hang up") is a signal sent to a process when its controlling terminal is closed. It was originally designed to notify the process of a serial line drop. The SIGHUP (“hang-up”) signal is used to report that the user's terminal is disconnected, perhaps because a network or telephone connection was broken.
  3. SIGSTOP: When you use SIGSTOP to a process, it will pause the process. It will not resume automatically unless you send a SIGCONT signal to it. This is great because it allows you to pause a process without terminating it.
  4. SIGCONT: The SIGCONT signal instructs the operating system to continue (restart) a process previously paused by the SIGSTOP or SIGTSTP signal.
  5. SIGKILL: Using kill command with SIGKILL signal sends a kill signal to end any process immediately when sent with a PID or a processname. It is a forceful way to terminate a or set of processes. This signal cannot be handled (caught), ignored or blocked.

  picture of man 7 signal:

  

• Describe SIGALRM

  1. SIGALRM is generated when the timer set by the alarm function goes off. SIGALRM is an asynchronous signal. The SIGALRM signal is raised when a time interval specified in a call to the alarm or alarmd function expires. Because SIGALRM is an asynchronous signal, the SAS/C library discovers the signal only when you call a function, when a function returns, or when you issue a call to sigchk . Generally SIGALRM is used to notify a process that the specified real-time interval has elapsed.

• Investigate the given code

  1. First, it sets an alarm for 5 seconds, then it prints the message "Looping forever . . .", and then it enters an infinite loop. The line after the while(1) will never be printed because the program is stuck in the infinite loop. After 5 seconds, the program will receive the SIGALRM signal and its execution will be terminated, since no signal handler has been set for it.
  2. 

• Modify the given program by handling SIGALRM

  1. [FILL HERE with your source code.]

• Write a program that handles Ctrl + C

  1. [FILL HERE with your source code.]