Proc_manager.c | Computer Science homework help

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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 cmdfilesleep 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).

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July 1, 2023

Distinguishing Inductive and Deductive Reasoning

Required Resources
Read/review the following resources for this activity:

· Textbook: Chapter 8, 9, 17 (Introduction)

· Lesson

· Minimum of 1 scholarly source (in addition to the textbook)

Click on the following tabs to review the concepts that will be addressed in this activity:

A valid structure is the way in which an argument is put together that assures it will pass the test of logical strength.

Deductive: In deductive arguments, the speaker asserts that her premises are true and, therefore, her conclusion must be accepted. Remember that in a deductive argument, logical strength does not depend on the literal truth of the premises. When we test for logical strength, we assume the premises are true. Once we determine that the argument is logically valid, we can then look at the actual – not presumed – truth of the premises.

Inductive: In inductive arguments, the speaker presents evidence that she claims support the probable truth of her conclusion – that her conclusion is the most likely true – and so you should accept it.

The Basic Structure of Deductive and Inductive Arguments
Argument examples:

Deductive Argument Example: “Tightening laws restricting the use and possession of firearms does not protect average law-abiding citizens; it only puts them at greater risk. Enforcing licensing restrictions, trigger locks, and waiting periods makes it more difficult for law-abiding citizens to defend themselves, and, as a result, encourages criminal activity. Only criminals benefit when ordinary citizens are deprived of their right to own a firearm and protect themselves, their homes, and their families" (Lott, 2000, p. 169)

Lott, J., (2000). More guns, less crime: Understanding crime and gun-control laws. University of Chicago Press.

The argument boils down to this:

· Laws that are obeyed by ordinary citizens and not obeyed by criminals are laws that put ordinary citizens at risk.

· Tight gun laws are laws that are obeyed only by ordinary citizens.

· Tight gun laws put ordinary citizens at risk.

However, the argument itself is composed of three intertwined syllogisms:

Only ordinary citizens are persons who respect tight gun laws.
Criminal persons are not ordinary citizens.
Therefore, criminals do not respect tight gun laws.

Tight gun laws restrict only ordinary citizens.
No criminal is an ordinary citizen.
No criminal is restricted by tight gun laws.

Laws that disfavor the good are laws that favor the bad.
Tight gun laws favor the bad.
Therefore, tight gun laws disfavor the good.

Notice that you cannot remove any of the “legs” and maintain the claim. Notice, also, that the reasons are closely connected and depend on or follow from each other. Notice, also, that the first premise (called the major premise) must be accepted as true, or the entire argument fails.

Inductive Argument: The United States is too dependent upon foreign oil. According to the U.S. Department of Energy, we rely on imported foreign oil for about 45% of our needs. Of the imported oil, most comes from Canada, but 22% comes from countries in the Middle East. Undeniably, this dependence shapes our foreign policy. We have vast oil reserves that could make us energy independent. Development of these resources would produce much-needed jobs, many of them in areas of the country suffering most from the recession. We should be developing an energy policy that makes us energy independent.

· Reason: We import 45% of our oil.

· Reason: Middle East oil imports shape our foreign policy.

· Reason: Our vast oil reserves could make us energy independent.

· Reason: Development of oil reserves could produce much needed jobs.

· Conclusion: For any or all of the above, independent reasons, we should become energy independent.

Notice that any one of these reasons, standing alone, could support the conclusions; they are not logically related to one another as they would be in a syllogism.

Initial Post Instructions
For the initial post, address the following:

· Find and post examples of deductive and inductive arguments. Do NOT use an argument example which clearly indicates it is an example of an inductive/deductive argument.

· For each example, evaluate its logical strength, using the concepts and ideas presented in the textbook readings, the lesson, and any other source you find that helps you to evaluate the validity (deductive) or strength (inductive) of the argument. You can use examples from the text, or you can find examples elsewhere.

oEditorials and opinion columns are a good source, as are letters to the editor. Blogs will also often be based on arguments.

oUse mapping and evaluative techniques to make sure it is an argument.

· Is it inductive or deductive? Explain why.

· Does it pass the tests of validity and strength? Explain.