mysh — A Unix Shell in C

A POSIX-compliant Unix shell built from scratch in C.

Features

• Run any system command (ls, cat, echo, pwd...)
• Pipes (ls | grep .c)
• Output redirection (echo hello > file.txt)
• Input redirection (cat < file.txt)
• Built-in commands: cd, exit, help
• Prompt shows current working directory

Build & Run

gcc main.c -o mysh ./mysh

Syscalls Used

Syscall	Purpose
fork()	create child process
execvp()	replace child with command
waitpid()	wait for child to finish
pipe()	connect two processes
dup2()	redirect input/output
chdir()	change directory
getcwd()	get current directory

What I Learned

• How Unix processes work
• How every shell on earth works under the hood
• File descriptors and I/O redirection
• Inter-process communication with pipes