42_codam_pipex

This project is the discovery in detail and by programming of a UNIX mechanism that you already know: pipes.

Usage

The pipex program will be executed as follows:

./pipex file1 cmd1 cmd2 file2

It must take 4 arguments:

• file1 and file2 are file names.

• cmd1 and cmd2 are shell commands with their parameters.

It must behave exactly the same as the shell command below:

$> < file1 cmd1 | cmd2 > file2

Constraints

Functions allowed: open, close, read, write, malloc, free, perror, strerror, access, dup, dup2, execve, exit, fork, pipe, unlink, wait, waitpid.

Return value

The return value of pipex should be the exit code of the second command.

Flowchart

Overview

Input parsing

Child process 1 & 2

Command execution

Parent process

Examples

a.

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

Should behave like:

< infile ls -l | wc -l > outfile

b.

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

Should behave like:

< infile grep a1 | wc -w > outfile