🐧 unix-system-programming

Deep-dive implementations of UNIX systems concepts: processes, signals, IPC, sockets

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📖 Overview

A collection of systems programming exercises covering the full UNIX API surface. Each module is self-contained with its own Makefile, annotated source, and test harness. Built to demonstrate mastery of low-level UNIX programming.

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🏗️ Modules

unix-system-programming/
├── 01-processes/
│   ├── fork_exec.c       # fork + execve + waitpid patterns
│   └── process_tree.c    # Build a process tree, print with indentation
├── 02-signals/
│   ├── signal_handler.c  # sigaction, SA_RESTART, signal masks
│   └── job_control.c     # SIGCHLD, SIGTSTP, fg/bg job tracking
├── 03-ipc/
│   ├── pipe_redir.c      # Pipes and dup2 for shell-style redirection
│   ├── shared_mem.c      # POSIX shm_open + mmap producer-consumer
│   └── message_queue.c   # POSIX mq_open for async messaging
├── 04-sockets/
│   ├── tcp_server.c      # Concurrent TCP server with poll()
│   └── unix_socket.c     # AF_UNIX datagram socket IPC
├── 05-threads/
│   ├── thread_pool.c     # POSIX threads + condition variables
│   └── rwlock.c          # Read-write lock from scratch
└── README.md

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🚀 Quick Start

git clone https://github.com/gitisabel/unix-system-programming
cd unix-system-programming/04-sockets
make
./tcp_server &
./tcp_client 127.0.0.1 8080

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🔑 Highlights

// Non-blocking poll()-based TCP server (04-sockets/tcp_server.c)
int epfd = epoll_create1(0);
epoll_ctl(epfd, EPOLL_CTL_ADD, listenfd, &ev);
while (1) {
    int n = epoll_wait(epfd, events, MAX_EVENTS, -1);
    for (int i = 0; i < n; i++) handle_event(&events[i]);
}

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🧪 Tests

Each module has a make test target that runs correctness checks and checks for fd/memory leaks with valgrind.

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📄 License

MIT © Isabel