Advanced UNIX Programing

Below is the list of some of system programs that I have written while doing my academic assignments:

1. File I/O (Lab1)

• Implement lseek behaviour using system calls like open(), close(), read(), write(), creat() etc..

2. Files and Directories (Lab2)

• Use of APIs like opendir(), file stat structure, readdir(), mkdir(), chmod(), chdir(), etc..
• Implementation of realpath() behaviour file stat structure information and other APIs available.
• Create a shared directory for usage with a purpose that any user (not super user) can create new files in this directory, but only the owner can delete his own files and everyone else can read all files.

3. File I/O & File Stat (Lab3)

• Using dup() function redirect stdin to file1 and stdout to file2. Read a line using scanf and write the same using printf. Verify the contents of both files.
• stat() function behaviour.
• Understanding umask() function.

4. Process Environment (Lab4)

• Understanding environment variables, adding and removing environment variables.
• Observing variable states after calling setjmp() and longjmp().

5. Process Control (Lab5)

• A program to demostate, A child process inherits real user id, real group id, effective user id and effective group id of the parent process, while process id and parent process id are not.
• A program to Verify whether it is possible for a child process to handle a file opened by its parent Immediately after the fork() call.
• Child and Parent behaviour after calling fork().

6. Process Control-Threding (Lab6)

• Write A program to take input from user for number of files to be scanned and word to be searched. write a multi threaded program to search the files and return pattern if found.
• A program to find number of CPUs, create that many threads and attach those threads to CPUs.

7. Process Control-Inheritance (Lab7)

• Program to demostrate, the child exec call inherits the file descriptors of parent if Close_on_exec is not set.
• Creating different processes using fork() for commands read from file.
• Use of SETUID for managing permissions.

8. Process Control-Waiting (Lab8)

• Understanding wait() system call.
• Call fork(). Let the child create a new session. Verify that the child becomes the process group leader and it does not have a controlling terminal.
• A program to verify that a parent process can change the process group ID of one of its children before the child performs an exec(), but not afterward.

9. Signals (Lab9)

• Playing with different signal mechanisms.