pipex

The pipex project is a C program that simulates a shell pipeline |.

It uses pipes | to connect commands, handles file redirection, and manages multiple processes.

The program takes two input files and a set of commands, then pipes the commands together and outputs the result.

Key Concepts

• Pipes: Used to pass the output of one command as input to another.

• Process Management: The program uses fork() to create child processes to execute commands, with communication happening through pipes.

• File Redirection: Reads from or writes to files by redirecting input/output.

• Environment Variables: Uses the PATH variable to locate commands in system directories.

• Error Handling: Displays an error message and exits the program if something goes wrong (e.g., invalid commands or failure to create pipes).

Functions Overview

Function	Description
left_process(char *argv[], char *envp[], int fd[])	Executes the first command in the pipeline and manages its redirection.
right_process(char *argv[], char *envp[], int fd[])	Executes the second command in the pipeline and manages its redirection.
execute_cmd(char *cmd, char *envp[])	Finds and runs a command by checking the system's PATH.
get_path(char *cmd, char *envp[])	Finds the full path of a command in the PATH directories.
error_message(char *message)	Displays an error message and exits the program if something goes wrong.

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How to Run

Make the project:

To compile the pipex project, run the following command:

$ make

Run the program:

To run the program, use the following format:

$ ./pipex file1 cmd1 cmd2 file2

• file1 is the input file for the first command.
• cmd1 is the first command to execute.
• cmd2 is the second command to execute.
• file2 is the output file where the result of the pipeline will be written.

Example:

$ ./pipex input.txt "cat" "grep keyword" output.txt

Rebuild:

To rebuild the project from scratch (after using fclean), run:

$ make re