ShelluMama: Unix Shell Clone

Features

• Basic command execution
• I/O redirection (<, >, >>)
• Command piping (|)
• Multiple commands (;)
• Logical operators (&&)
• Command history
• Signal handling

Building the Shell

gcc -o shell shell.c

Running the Shell

./shell

Feature Testing Guide

Basic Shell Functionality

# Test simple commands
ls
pwd
echo "Hello World"

# Test built-in commands
cd /tmp
pwd
cd ~
pwd

I/O Redirection

# Input redirection
cat < /etc/passwd

# Output redirection
ls -la > output.txt
cat output.txt

# Output redirection with append
echo "First line" > append_test.txt
echo "Second line" >> append_test.txt
cat append_test.txt  # Should show both lines

Command Piping

# Simple pipe
ls -la | grep ".txt"

# Multiple pipes
cat /etc/passwd | grep "root" | wc -l

# Complex piping
ls -la | grep "." | sort -r | head -n 3

Multiple Commands (Semicolon)

# Execute multiple commands in sequence
echo "Testing" ; ls ; pwd

Logical Operations (&&)

# Second command runs only if first succeeds
ls && echo "ls succeeded"
ls /nonexistent && echo "This won't print"

# Chain multiple commands with &&
mkdir test_dir && cd test_dir && pwd && cd .. && rm -r test_dir

Command History

# Run several commands, then:
history

Signal Handling

# Start a long-running command and press CTRL+C
sleep 10
# Press CTRL+C while it's running

# Verify the shell is still running by executing another command
echo "Shell is still alive"

Combined Features

# Redirection with pipes
ls -la | grep ".txt" > text_files.txt

# Multiple commands with different features
echo "Testing" > test.txt ; cat test.txt | grep "Test" && echo "Found it!"

# Complex test case
find / -name "*.txt" 2>/dev/null | grep "etc" | sort | head -n 5 > result.txt && cat result.txt

Built-in Commands

• cd [directory]: Change current directory
• history: Show command history
• exit: Exit the shell

Error Handling

The shell provides error messages for:

• Command not found
• Permission denied
• File not found
• Other system errors

Notes

• CTRL+C terminates the current command but not the shell
• The shell supports up to 100 history entries
• Pipes can be chained up to 10 times in a single command