Systems Programming Assignment 8: Process Control Solution

Warning







Warning: do NOT utilize the fox machines for performing or testing this assignment! You can and WILL cause a fork()-bomb, causing the system(s) to become unstable and unusable.




Instead, you MUST utilize servers hen04.cs.utsarr.net or hen03.cs.utsarr.net. Note that these servers are accessible only in the following ways:




Within the UTSA network (i.e., using the on-campus network);



via VDI from home; or,



via connecting to a fox machine first, then proceeding to SSH into one of these two hen machines.



If either server becomes unstable or unusable due to a student’s out-of-control project, email me to alert me to the situation and I will have the system(s) reset.










For this assignment, you will use C’s process control functions to exercise basic process creation.




Your program should have the following functionality:







Concurrency







Given up to six commands separated by commas (a comma will be its own token, with whitespace around it) and any number of arguments each, execute all commands concurrently (i.e., in parallel and not one after the other).




Each process (excluding the parent) should print their PID followed by their PPID followed by their command without arguments to stderr. Any normal behavior by the command issued should remain the same. You do not need to account for redirection or pipelining.




Your program should not produce orphans. Toward verification of this, if a process’s PPID is 1, it is an orphan that has been adopted by the init process. In solving this problem, be sure that your child processes still run concurrently. Do not wait for one process to complete before starting a new one.




Example




assign8 ls -a , pwd , cat hello.txt PID: 35003, PPID: 35002, CMD: ls PID: 35004, PPID: 35002, CMD: pwd






Assignment 8: Process Control Page 1 of 3

PID: 35005, PPID: 35002, CMD: cat




/home/ssilvestro




.. courses Desktop Downloads this is the contents of hello.txt



Note that since the processes are happening in parallel, the order of the output is not guaranteed.







Compiling Your Program







Your submission will include a makefile so the following command can be used to compile your code.




$ make assign8




This should produce an executable file named assign8. For more information about the make utility, check the related document on Blackboard.




If you attempt the extra credit, $ make assign8-2 should compile the extra credit portion to assign8-2.




Extra Credit (10 points)







Create a second program, assign8-2 which takes exactly two commands, with any number of arguments each, and separated by a comma. The program should pipe the output of the first command to the second using dup2().




Example




assign8-2 ls -l , sort -k5 -n should behave as
$ ls -l | sort -k5 -n




Extra credit is not given to late assignments. All requirements must be met for both parts of the assignment to qualify for extra credit.




Assignment Data







This assignment does not include sample input files since it will only take arguments.







Program Files







Your submission should consist of up to five files:




assign8.c - the main file which is compiled (required)









Assignment 8: Process Control Page 2 of 3
assign8.h - an optional header file if necessary



assign8-2.c - the main file which is compiled for extra credit (required for extra credit)



assign8-2.h - an optional header file if necessary



Makefile - the makefile to make the assign8 executable (required).






Submission







Turn your assignment in via Blackboard. Your zip file, named abc123.zip should contain only the files described above.




If you attempt the extra credit, name your file abc123_EC.zip. Without the _EC, your submission will be graded as normal.