Pipex

Implementation of Unix pipe behavior, allowing sequential command execution.

Description

The program simulates the behavior of the Unix pipe (|). It takes two commands as arguments and executes the first one, passing its standard output as standard input to the second, allowing input from a file and output to a file.

Functionality

Shell equivalence:

./pipex infile cmd1 cmd2 outfile
# Is equivalent to:
< infile cmd1 | cmd2 > outfile

Included Files

General structure:

• pipex.c - Main function and control logic
• pipex.h - Header file
• Utility files
• Directory libft/ - Custom library

Compilation

make              # Compile pipex
make clean        # Clean object files
make fclean       # Clean everything
make re           # Recompile from scratch

Usage

./pipex infile "command1" "command2" outfile

Example

./pipex input.txt "cat" "grep word" output.txt
# Reads input.txt, passes it to cat, then to grep, and writes to output.txt

Arguments

Argument	Description
infile	Input file (must exist)
cmd1	First command to execute
cmd2	Second command to execute
outfile	Output file (created or overwritten)

Requirements

• C compiler (gcc, clang, etc.)
• Make
• Linux or macOS
• Access to system commands (cat, grep, etc.)

Features

• Uses pipes for inter-process communication
• Child process forking
• Standard input/output redirection
• File and command error handling
• Executable search in PATH

Process Management

The program:

1. Opens the input file
2. Creates a pipe
3. Forks a child process to execute cmd1
4. Forks another child process to execute cmd2
5. Waits for both processes to finish
6. Closes files and pipes

Error Handling

• Validates input file existence
• Checks read/write permissions
• Handles commands not found
• Reports system errors appropriately

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Last updated: December 2025