Custom Command Shell

A custom command shell that supports both interactive and batch modes. It includes built-in commands such as exit, cd, and alias, as well as support for input/output redirection.

Features

• Interactive Mode: Run the shell interactively, executing commands one at a time.
• Batch Mode: Read and execute commands from a script file in batch mode.
• Built-in Commands:
  • exit: Terminate the shell.
  • cd: Change the current working directory.
  • alias: Create and manage command aliases.
• I/O Redirection: Redirect input and output for commands.

Getting Started

Prerequisites

• Your system should have a C compiler installed (e.g., GCC).

Build

make

Run Interactive Mode

./newshell

Run Batch Mode

./newshell batchFile.txt

Usage

Interactive Mode

1. Launch the shell.
2. Enter commands interactively.
3. Use built-in commands (exit, cd, alias) and I/O redirection.

$ ./newshell
Shell> ls -l
... (output)
Shell> cd /path/to/directory
Shell> exit

Batch Mode

1. Prepare a script file with commands.
2. Run the shell with the script file.

./newshell batchFile.txt

Built-in Commands

1. exit Terminate the shell. If the exit command is on the same line with other commands, the other commands will execute (and finish) before shell is exited.

Shell> exit

2. cd Change the current working directory.

Shell> cd /path/to/directory

3. alias Define shortcuts for commands using alias alias_name='command'. Use alias with no arguments to display all existing aliases. Remove a single alias with alias -r alias_name or all defined aliases with alias -c. This custom alias command substitutes a given string for a command, resembling the bash alias but implemented as a built-in command for proper shell execution control.

Shell> alias 5='ls -al'
Shell> 5
... (output of 'ls -al' command)

I/O Redirection

Redirect input and output for commands.

Shell> ls > output.txt
Shell> cat < input.txt