Examples&Exercises:

• Complete the following codes if necessary, then compile and run the code.
• Analyze the code and output.

1. Semaphores for Threads; http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/job-queue3.cjob-queue3.c
   • Complete the code.
   • The queue is controlled with a semaphore. Do we have any synchronization problem any more?
2. Shared Memory; http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/shm.cshm.c
   • Study and analyze the code.
   • During/after execution, give the following commands

     $ ipcs -m
     $ ipcrm shm SHMID
     

     for the cases
     • do that after execution;
     • put a sleep inside the code;
     • do not deallocate shared memory segment.
3. Mapped Memory; http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/mmap-write.cmmap-write.c, http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/mmap-read.cmmap-read.c
   • Study and analyze the code.
   • Apply the following procedure

     $ ./mmap-write /yourdirectory/integer-file 
     $ cat /yourdirectory/integer-file 
     42 
     $ ./mmap-read /yourdirectory/integer-file 
     value: 42 
     $ cat /yourdirectory/integer-file 
     84
     

4. Pipes;
   • Communication between parent and child processes; http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/pipe.cpipe.c,
   • Redirecting the standard input, output, and error streams; http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/dup2.cdup2.c.
   • Study and analyze the codes and outputs.
5. FIFOs;
   • Creating a named pipe,

     $ mkfifo /yourdirectory/fifo 
     $ ls -l /yourdirectory/fifo
     

   • In one window, read from the FIFO by invoking the following:

     $ cat < /yourdirectory/fifo
     

   • In a second window, write to the FIFO by invoking this:

     $ cat > /yourdirectory/fifo
     

   • Then type in some lines of text. Each time you press Enter, the line of text is sent through the FIFO and appears in the first window. Close the FIFO by pressing Ctrl+D in the second window.
   • Remove the FIFO with this line:

     $ rm /yourdirectory/fifo