UNIX I/O_Assignment 6 Solution

Assignment #6: UNIX I/O
 The purpose of this assignment is to practice making UNIX I/O system calls in C.  In a multiplexed manner, your main process will  read from multiple files, and  read from the standard input (the terminal).  Create five pipes and spawn five child processes.  Connect a pipe to each child process.  Each child process should write to its pipe.  The parent process should read from all the pipes.
Computer Science Dept. Spring 2015: April 14
CS 149: Operating Systems © R. Mak
2
Assignment #6, cont’d
 Each of the first four child processes should generate time stamped messages to the nearest 1000th of a second (time starts at 0): 0:00.123: Child 1 message 1 0:02.456: Child 1 message 2 etc. and write the messages one at a time to its pipe.
 Sleep for a random time of 0, 1, or 2 seconds between messages.  Terminate the process after 30 seconds.
Computer Science Dept. Spring 2015: April 14
CS 149: Operating Systems © R. Mak
3
Assignment #6, cont’d
 Meanwhile, the fifth child process should repeatedly prompt at the terminal (standard out) and read one line of input (standard in) typed by the user.
 Write the message (with time stamp) to its pipe.  Immediately prompt for the next message.  Terminate the process after 30 seconds.
Computer Science Dept. Spring 2015: April 14
CS 149: Operating Systems © R. Mak
4
Assignment #6, cont’d
 After spawning the child processes, the parent process should repeatedly read lines from the pipes.  Use the select() system call to determine whether any of the pipes has any input.
Read the “man” pages about select() .
Computer Science Dept. Spring 2015: April 14
CS 149: Operating Systems © R. Mak
5
Assignment #6, cont’d
 Write the lines to an output file output.txt in the order that they were read.  Prepend each line with a time stamp to the nearest 1000th of a second.
 Therefore, each line with have two time stamps.  The first time stamp from the parent process.  Followed by the child process’s time stamp.
Computer Science Dept. Spring 2015: April 14
CS 149: Operating Systems © R. Mak
6
Assignment #6, cont’d
 File output.txt will contain a mixture of lines from the child processes.
 Terminate the main process after all the child processes have terminated.
Computer Science Dept. Spring 2015: April 14
CS 149: Operating Systems © R. Mak
7
Assignment #6, cont’d
 Email me the zip file   Your C source files  Your output.txt file  A brief report describing any issues you encountered.  Name the zip file after your team.  Example: SuperCoders.zip
 Subject line: CS 149-section number Assignment #6 team name