🔗 pipex

A Unix pipe emulator using fork, execve, and pipe.

📌 Description

pipex is a 42 School project that recreates shell-like piping between commands. It simulates the behavior of:

< file1 cmd1 | cmd2 > file2

The program replicates this using system-level calls like fork, execve, pipe, and file I/O redirection. It helps build a deep understanding of Unix internals, process management, and inter-process communication.

⚙️ Features

• Executes two commands connected via a pipe
• Supports input/output file redirection
• Uses only low-level system calls (no popen or system())
• Handles error reporting and command path resolution

🚀 Usage

./pipex infile "cmd1" "cmd2" outfile

💡 Example

./pipex input.txt "grep hello" "wc -l" output.txt

Which behaves like:

< input.txt grep hello | wc -l > output.txt

🔧 Requirements

• Only allowed to use:
  open, close, read, write, malloc, free, access, dup, dup2, execve, exit, fork, pipe, unlink, wait, waitpid, perror, strerror
• No system() or popen() calls

📘 Concepts Learned

• 🧵 Inter-Process Communication (IPC) using pipes
• 🧬 Process management: creating child processes with fork()
• 🚪 File descriptor redirection using dup2()
• 🧠 Command execution with execve() and path resolution
• 🗂️ File I/O operations (open, read, write, close)
• 🔄 Error handling and custom message reporting
• 📂 Environment parsing and working with PATH
• ♻️ Memory management and resource cleanup
• ⚙️ Debugging complex flows involving multiple processes