Pipex

Description

The pipex project aims to provide an understanding of Unix processes and inter-process communication through pipes. The goal is to replicate the shell command piping functionality, allowing the output of one command to be used as the input for another. This project serves as an excellent exercise in system programming, focusing on process management, file operations, and error handling.

Objective

The main objective of this project is to create a program that behaves like the shell command below:

< file1 cmd1 | cmd2 > file2

Your program should be executed as follows:

./pipex file1 cmd1 cmd2 file2

Arguments

file1 : The input file.
cmd1 : The first shell command to execute.
cmd2 : The second shell command to execute.
file2 : The output file.

Example

Running the command:

./pipex infile "ls -l" "wc -l" outfile

Should produce the same result as the shell command:

< infile ls -l | wc -l > outfile

Requirements

Mandatory Part

Implement the program to handle exactly two commands with a single pipe.
Handle errors gracefully to ensure the program does not crash unexpectedly.
Ensure there are no memory leaks.

Bonus Part

Support multiple pipes with more than two commands:

./pipex file1 cmd1 cmd2 cmd3 ... cmdn file2

This should mimic the shell command:

< file1 cmd1 | cmd2 | cmd3 ... | cmdn > file2

Support the "here_doc" functionality:

./pipex here_doc LIMITER cmd cmd1 file

This should mimic the shell command:

cmd << LIMITER | cmd1 >> file

Allowed Functions

open, close, read, write
malloc, free, perror, strerror, access
dup, dup2, execve, exit, fork, pipe
unlink, wait, waitpid
Your own ft_printf or an equivalent
Libft is allowed

Project Structure

Makefile: Compilation rules.
Source files (*.c): Implementation of the pipex program.
Header files (*.h): Declarations for functions and macros.

Compilation

Use the provided Makefile to compile the project:

make

This will create the pipex executable.

Usage

Run the program with the required arguments:

./pipex file1 cmd1 cmd2 file2

Examples

./pipex infile "grep a1" "wc -w" outfile

This should produce the same result as:

< infile grep a1 | wc -w > outfile

Error Handling

Ensure to handle and report errors properly without causing segmentation faults, bus errors, or double frees. Check for proper file permissions and existence.
Manage memory to avoid leaks.

Learning Outcomes

Through this project, you will gain a deeper understanding of:

Process creation and management using fork.
Inter-process communication using pipe.
Redirecting input and output with dup and dup2.
Executing commands with execve.
Handling file operations and errors in Unix.

Conclusion

The pipex project is a hands-on approach to learning the intricacies of process communication and management in Unix-like systems. It strengthens your understanding of system-level programming and equips you with skills essential for advanced programming tasks.

DevJ2K/pipex_v2