Proc_manager.c | Computer Science homework help

When a UNIX-like system starts up, it runs init. Nowadays this is a program called systemd on UNIX-like systems. On Mac the similar system manager is called launchd. It runs under PID of 1 and is an ancestor of all other processes. You can see the process with command “ps aux”. If a process is left as an orphan (its parent dies), it gets reassigned as a child of PID 1. These service programs (init, systemd or launchd) are running in the background; on UNIX-like OSs these are commonly referred to as daemons and generally have names ending with the letter “d.” These programs ensure that things start up properly and stay running.  If a process crashes systemd (or launchd) can detect this and start it back up.
You will develop a proc_manager program that reads in the commands to execute from an input file one-by-one. You will read one command and its parameters per each line. Then the proc_manager program will start up the process and “babysit” it.You will run each command in a child process using exec (or one of its variants) and the parent process will wait for each exec to complete. For each child process there will be log messages written to output and error files, which are named after its index in the sequence of commands read in. For example, process #1 will have logs written to 1.out and 1.err. Upon start, the string “Starting command INDEX: child PID pid of parent PPID” will be logged to the corresponding output file 1.out. You can retrieve PID and PPID through the return value of fork() or getpid() or getppid().You can use dup2() to make file handle 1 (stdout) go to a file X.out and handle 2 (stderr) go to a file X.err. Note: new executions of a command should append to the previous output and error files, such as 1.out, rather than overwrite them.
Timer for each process: you can include the timer.h library and use timer to record the start time of spawning each child process in the parent. Upon finish of an exec (either a successful finish or termination via a signal), the process should record the finish runtime, and it should write to the output file the string “Finished at FIN, runtime duration DUR” where FIN is the finish time and DUR is the duration of the execution.
Each time a process finishes, the message “Exited with exitcode = X” should be written to the error file of the process. X is the process exit code. If the process was killed with a signal, then “Killed with signal S” should be written to the error file. S is the signal number that killed the process. This information is gathered using the status parameter of the wait() system call. If the program cannot be started (exec fails), use perror(“name of command“) to get the error message and command name and write them to the command’s error file. Processes that encounter an invalid command (exec fails) should have an exit code of 2. Remember the exit code of 0 indicates success. Exit codes other than 0 indicate some failure, including a termination via a kill signal.Here is an example run:

./proc_manager cmdfile

Where cmdfile contains:

prompt> cat cmdfile

sleep 5

ls -latr

pwd

sleep 1

wc /etc/passwd

The parent will re-start the executable if the command took more than two seconds to complete. Therefore, a process restarts as long as its last execution took more than 2 seconds. If a process completed within less than 2 seconds after starting, proc_manager will not restart it and will print a message “spawning too fast” to the error file for the process. If it was terminated by a signal right after it started, or it had some other failure that caused it to exit immediately, it won’t restart, since it exited immediately.
proc_manager runs until there are no more processes running. In this example the ls and wc commands won’t get restarted because they finish right after they are started. The sleep runs for 3 seconds, so proc_manager will keep restarting it, unless we do “pkill sleep” in another terminal. If we do pkill fast enough, proc_manager will detect the quick duration and exit and not restart it. If any process has no child process then wait() returns immediately “-1”, thus you can continue until wait() returns -1.

Grading

code compiles without errors or warnings -Wall on VirtualBox10%

correctly uses fork()10%

correctly uses wait*()10%

correctly uses dup2()10%

a version of exec is used correctly10%

the exit and signal codes and spawning messages are printed correctly10%

all processes run in parallel10%

an output and error file is created for each command10%

code is commented and indented (use of white space)10%

zip file contains proc_manager.c10%

Submission

Upload a zip file called proj3.zip that contains your source files that are needed to compile and run on VirtualBox (including proc_manager.c).

Order a unique copy of this paper
(550 words)

Approximate price: $22

Basic features
  • Free title page and bibliography
  • Unlimited revisions
  • Plagiarism-free guarantee
  • Money-back guarantee
  • 24/7 support
On-demand options
  • Writer’s samples
  • Part-by-part delivery
  • Overnight delivery
  • Copies of used sources
  • Expert Proofreading
Paper format
  • 275 words per page
  • 12 pt Arial/Times New Roman
  • Double line spacing
  • Any citation style (APA, MLA, Chicago/Turabian, Harvard)

Our guarantees

We value our customers and so we ensure that what we do is 100% original..
With us you are guaranteed of quality work done by our qualified experts.Your information and everything that you do with us is kept completely confidential.

Money-back guarantee

You have to be 100% sure of the quality of your product to give a money-back guarantee. This describes us perfectly. Make sure that this guarantee is totally transparent.

Read more

Zero-plagiarism guarantee

The Product ordered is guaranteed to be original. Orders are checked by the most advanced anti-plagiarism software in the market to assure that the Product is 100% original. The Company has a zero tolerance policy for plagiarism.

Read more

Free-revision policy

The Free Revision policy is a courtesy service that the Company provides to help ensure Customer’s total satisfaction with the completed Order. To receive free revision the Company requires that the Customer provide the request within fourteen (14) days from the first completion date and within a period of thirty (30) days for dissertations.

Read more

Privacy policy

The Company is committed to protect the privacy of the Customer and it will never resell or share any of Customer’s personal information, including credit card data, with any third party. All the online transactions are processed through the secure and reliable online payment systems.

Read more

Fair-cooperation guarantee

By placing an order with us, you agree to the service we provide. We will endear to do all that it takes to deliver a comprehensive paper as per your requirements. We also count on your cooperation to ensure that we deliver on this mandate.

Read more

Calculate the price of your order

550 words
We'll send you the first draft for approval by September 11, 2018 at 10:52 AM
Total price:
$26
The price is based on these factors:
Academic level
Number of pages
Urgency