MyShell – Custom UNIX-like Shell in C

A fully functional custom UNIX-like shell implemented in C, built from scratch without relying on existing shell code.
Implements core shell features such as command execution, directory navigation, piping, redirection, and prompt customization.

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Features

• Command Execution – Runs any executable in the system’s $PATH using execvp
• Multiple Commands per Line – Separate with ;
• Change Directory – Built-in cd with home (~) expansion
• Prompt Customization – Shows shortened current working directory
• Exit Methods – Type exit or press Ctrl-D
• Pipes – Basic single-pipe support using popen()
• I/O Redirection – < for input, > for output
• Error Handling – Graceful handling of invalid commands and arguments

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File Overview

• main.c – Entry point and main program loop
• shell.c – Core shell logic (command parsing, execution, pipes, redirection)
• shell.h – Header file for shared functions and constants
• makefile – Build automation (make, make clean)
• .gitignore – Ignore compiled binaries and temp files

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Quick Start

1. Build

make

Produces the myshell binary.

2. Run

./myshell

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Usage Examples

ls -l
cd Documents
echo "Hello, World!" > output.txt
cat < input.txt | grep keyword
pwd; whoami; date

Exit the shell:

exit

or press Ctrl-D.

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Clean Build Artifacts

make clean

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Notes

• Designed for POSIX-compliant systems (macOS, Linux)
• No external dependencies beyond a C compiler
• Simple single-pipe implementation; multiple pipes can be added with minor parsing changes

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Skills Demonstrated

• Low-level C systems programming
• Process control with fork(), execvp(), and wait()
• Command parsing using strsep() and tokenization
• File descriptor manipulation for I/O redirection
• Basic inter-process communication with popen()
• Terminal prompt customization

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Author

Developed by Andrew Choi, Victor Kamrowski, and Tony Chen.

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Repository Note

This repository was imported in a single commit from a private development repo where it was originally created and maintained.
The commit history was reset to remove unrelated school references.