README

NJU OS Labs 2018

This is the personal implementation of the 2018 spring OS Labs at Nanjing University instructed by Dr. Jiang Yanyan. The project is opensourced under GPL v3.

* Warning to my dear classmates *
You will be at your own risk if you use any of the code in this repository. 

= pstree.c =

This project implemented a miniature of the classic UNIX command pstree by reading kernel information from the /proc directory(thus makes it only compatible with Linux), which lists all the processes running in the form of a tree. The program implemented 3 options wwhich are
  -p, --show-pids:      which prints out the PID of each process.
  -n, --numeric-sort:   which sorts all the processes by their PIDs.
  -k, --kernel-threads: which prints out the kernel threads along side with normal output.
Also a -V or --version option is available to provide version informaion of the program.

= perf.c =

Performance evaluator which lists all the system calls during the process and the time they cost. (It is in fact no more than a *beautiful* shell of "strace -T")

= crepl.c=

C read-evaluate-print-loop. It takes the input of a valid C code (but with some limitations) to provide an interactive C code shell. Limitations includes
1. Only int functions are accepted and registered.
2. All other code will be regarded as an expression.
3. A function or an expression must take and only take a single line.
4. All other input's results will be undefined.