42_pipex

About

Pipex is a project written in C that aims to recreate the functionality of pipes in the Unix shell. The program takes a command-line input in the form of:

./pipex infile cmd1 cmd2 outfile

This is designed to behave like the Unix command:

< infile cmd1 | cmd2 > outfile

Here's how it works:

infile: Input file to be read from.
cmd1: First command to be executed.
cmd2: Second command to be executed.
outfile: Output file to be written to.

Examples

To count the number of lines in a file:

# pipex version
./pipex infile "ls -l" "wc -l" outfile
# Unix version
< infile ls -l | wc -l > outfile

To count the number of words containing 'a' in a file:

# pipex version
./pipex infile "grep a" "wc -w" outfile
# Unix version
< infile grep a | wc -w > outfile

Bonus functionalities

Handling multiple pipes:

# pipex_bonus version
./pipex_bonus infile cmd1 cmd2 cmd3 ... cmdn outfile
# Unix version
< infile cmd1 | cmd2 | cmd3 ... | cmdn > outfile

Support for "here_doc" syntax:

# pipex_bonus version
./pipex_bonus here_doc LIMITER cmd cmd1 file
# Unix version
cmd << LIMITER | cmd1 >> file

Usage

To create pipex, run the following command inside the pipex folder:

make

To create pipex_bonus, run the following command inside the pipex folder:

make bonus

Allowed functions

The following functions were allowed for use in this project:

Function	Man	Short Description
open	man 2 open	Opens a file or device and returns a file descriptor
close	man 2 close	Closes a file descriptor
read	man 2 read	Reads data from a file descriptor
write	man 2 write	Writes data to a file descriptor
malloc	man 3 malloc	Allocates a block of memory dynamically
free	man 3 free	Deallocates a block of memory
perror	man 3 perror	Prints a descriptive error message to stderr based on the value of errno
strerror	man 3 strerror	Returns a string describing the error code passed as argument
access	man 2 access	Checks the accessibility of a file or directory
dup	man 2 dup	Duplicates a file descriptor
dup2	man 2 dup2	Duplicates a file descriptor to a specified new descriptor
execve	man 2 execve	Executes a program
exit	man 3 exit	Terminates the calling process
fork	man 2 fork	Creates a new process
pipe	man 2 pipe	Creates a pipe, a unidirectional communication channel
unlink	man 2 unlink	Deletes a name from the filesystem
wait	man 2 wait	Waits for a child process to terminate
waitpid	man 2 waitpid	Waits for a specific child process to terminate