sophiakoulen / pipex

Reproducing Bash's pipe operator

pipex

introduction

The aim of this project is to start working with Unix processes. In this project, we have to reproduce Bash's pipe operator (|), whose effect is to redirect a commands output to be the input of another command.

how to use

After running make in the project's directory, you can run commands that have the following form:

./pipex input.txt cmd1 cmd2 output.txt

is equivalent to Bash's:

< input.txt cmd1 | cmd2 > output.txt

I support multiple pipes, so:

./pipex input.txt cmd1 cmd2 cmd3 cmd4 output.txt

is equivalent to Bash's:

< input.txt cmd1 | cmd2 | cmd3 | cmd4 > output.txt

authorized functions

• open: opens a file and returns a file descriptor
• close: closes a file pointed to by a file descriptor
• read: reads from a file descriptor
• write: writes to a file descriptor
• malloc: allocates memory on the heap
• free: frees memory on the heap
• perror: prints an error message to stderr
• strerror: returns string corresponding to an error code
• access: checks if we have access to a given filename
• dup: duplicates a file descriptor
• dup2: duplicates a file descriptor and gives it the value we want
• execve: replaces the current process with the program given
• exit: exits a program with a given return status
• fork: duplicates the current process
• pipe: creates a pair of file descriptors that can allow two processes to communicate
• unlink: remove a file
• wait: waits for a child process to finish
• waitpid: waits for a given child process to finish