Documentation
Æsh Readline
Prompt

Prompt

The Prompt class represents the prompt displayed to users before input. It supports simple text prompts, styled prompts with colors, and masked input for passwords.

Overview

A prompt is displayed each time the shell waits for user input. Æsh Readline provides flexible prompt configuration:

// Simple string prompt
Prompt prompt = new Prompt("$ ");

// Prompt with mask character for passwords
Prompt prompt = new Prompt("Password: ", '*');

// Styled prompt with colors
Prompt prompt = new Prompt(new TerminalString("[user@host]$ ", 
        new TerminalColor(Color.GREEN, Color.DEFAULT)));

Constructors

Basic Prompt 

// Simple text prompt
Prompt prompt = new Prompt("myapp> ");

Prompt with Mask

Used for password input where characters should be hidden:

// Characters are replaced with '*'
Prompt prompt = new Prompt("Password: ", '*');

// Characters are hidden (no echo)
Prompt prompt = new Prompt("Secret: ", '\0');

Prompt with TerminalString

For styled prompts with colors:

TerminalString styledPrompt = new TerminalString(
        "[admin]# ",
        new TerminalColor(Color.RED, Color.DEFAULT),
        CharacterType.BOLD
);
Prompt prompt = new Prompt(styledPrompt);

Prompt with Multiple TerminalStrings

For complex multi-part prompts:

List<TerminalString> parts = Arrays.asList(
        new TerminalString("[", new TerminalColor(Color.WHITE, Color.DEFAULT)),
        new TerminalString("user", new TerminalColor(Color.GREEN, Color.DEFAULT)),
        new TerminalString("@", new TerminalColor(Color.WHITE, Color.DEFAULT)),
        new TerminalString("host", new TerminalColor(Color.BLUE, Color.DEFAULT)),
        new TerminalString("]$ ", new TerminalColor(Color.WHITE, Color.DEFAULT))
);
Prompt prompt = new Prompt(parts);

Prompt Properties

PropertyTypeDescription
promptStringThe prompt text
maskCharacterMask character for input (null if no masking)
ansiStringTerminalStringStyled prompt string
ansiStringsList<TerminalString>Multiple styled prompt parts

Methods

getPromptAsString()

Returns the prompt text without ANSI codes:

Prompt prompt = new Prompt("[user]$ ");
String text = prompt.getPromptAsString(); // "[user]$ "

getMask()

Returns the mask character, or null if no masking:

Prompt prompt = new Prompt("Password: ", '*');
Character mask = prompt.getMask(); // '*'

isMasking()

Returns true if the prompt uses input masking:

Prompt prompt = new Prompt("Password: ", '*');
boolean masking = prompt.isMasking(); // true

hasANSI()

Returns true if the prompt uses ANSI styling:

Prompt prompt = new Prompt(new TerminalString("$ ", Color.GREEN));
boolean hasAnsi = prompt.hasANSI(); // true

copy()

Creates a copy of the prompt:

Prompt original = new Prompt("$ ");
Prompt copy = original.copy();

Using Prompts

With Readline 

Readline readline = ReadlineBuilder.builder().build();

Prompt prompt = new Prompt("myapp> ");
readline.readline(connection, prompt, input -> {
    // Handle input
});

With AeshConsoleRunner 

AeshConsoleRunner.builder()
        .command(MyCommand.class)
        .prompt("[myshell]$ ")  // Simple string
        .start();

// Or with a Prompt object
Prompt prompt = new Prompt(new TerminalString("$ ", Color.CYAN));
AeshConsoleRunner.builder()
        .command(MyCommand.class)
        .prompt(prompt)
        .start();

Dynamic Prompts

Create prompts that change based on context:

public class DynamicPromptShell {
    private String currentDirectory = "/home/user";
    private String username = "user";
    
    public void start() {
        AeshConsoleRunner.builder()
                .command(CdCommand.class)
                .prompt(this::createPrompt)
                .addExitCommand()
                .start();
    }
    
    private Prompt createPrompt() {
        String promptText = String.format("[%s@%s]$ ", username, currentDirectory);
        return new Prompt(new TerminalString(promptText, Color.GREEN));
    }
    
    public void setCurrentDirectory(String dir) {
        this.currentDirectory = dir;
    }
}

Styled Prompts

Colors 

// Foreground color only
new TerminalString("$ ", new TerminalColor(Color.GREEN, Color.DEFAULT))

// Foreground and background
new TerminalString("$ ", new TerminalColor(Color.WHITE, Color.BLUE))

// Using RGB colors (24-bit)
new TerminalString("$ ", new TerminalColor(new Color(255, 100, 50), Color.DEFAULT))

Text Styles 

// Bold text
new TerminalString("$ ", Color.DEFAULT, CharacterType.BOLD)

// Italic text
new TerminalString("$ ", Color.DEFAULT, CharacterType.ITALIC)

// Underlined text
new TerminalString("$ ", Color.DEFAULT, CharacterType.UNDERLINE)

// Combined styles
new TerminalString("$ ", 
        new TerminalColor(Color.RED, Color.DEFAULT),
        CharacterType.BOLD,
        CharacterType.UNDERLINE)

Multi-Part Styled Prompts 

List<TerminalString> promptParts = Arrays.asList(
        // Username in green
        new TerminalString(username, new TerminalColor(Color.GREEN, Color.DEFAULT)),
        // Separator
        new TerminalString(":", Color.DEFAULT),
        // Directory in blue
        new TerminalString(currentDir, new TerminalColor(Color.BLUE, Color.DEFAULT), CharacterType.BOLD),
        // Prompt symbol based on user type
        new TerminalString(isRoot ? "# " : "$ ", Color.DEFAULT)
);
Prompt prompt = new Prompt(promptParts);

Password Input

Basic Password Prompt 

// Reading password in a command
@Override
public CommandResult execute(CommandInvocation invocation) throws InterruptedException {
    Shell shell = invocation.getShell();
    
    // Password input with asterisk mask
    String password = shell.readLine(new Prompt("Password: ", '*'));
    
    // Authenticate...
    return CommandResult.SUCCESS;
}

Hidden Input (No Echo) 

// Use null character for completely hidden input
Prompt hiddenPrompt = new Prompt("API Key: ", '\0');
String apiKey = shell.readLine(hiddenPrompt);

Confirmation Pattern 

@Override
public CommandResult execute(CommandInvocation invocation) throws InterruptedException {
    Shell shell = invocation.getShell();
    
    // Get password
    String password = shell.readLine(new Prompt("Enter new password: ", '*'));
    String confirm = shell.readLine(new Prompt("Confirm password: ", '*'));
    
    if (!password.equals(confirm)) {
        invocation.println("Passwords do not match!");
        return CommandResult.FAILURE;
    }
    
    // Save password...
    invocation.println("Password updated successfully.");
    return CommandResult.SUCCESS;
}

Complete Example 

import org.aesh.readline.*;
import org.aesh.readline.terminal.formatting.*;
import org.aesh.terminal.Connection;
import java.util.Arrays;
import java.util.List;

public class StyledPromptExample {
    
    public static void main(String[] args) {
        Connection connection = /* obtain connection */;
        Readline readline = ReadlineBuilder.builder().build();
        
        // Create a fancy prompt
        Prompt prompt = createFancyPrompt("user", "/home/user");
        
        readline.readline(connection, prompt, input -> {
            if (input != null && !input.trim().isEmpty()) {
                System.out.println("You entered: " + input);
            }
            
            // Continue reading
            readline.readline(connection, prompt, this);
        });
    }
    
    private static Prompt createFancyPrompt(String user, String directory) {
        List<TerminalString> parts = Arrays.asList(
                // Opening bracket
                new TerminalString("[", 
                        new TerminalColor(Color.WHITE, Color.DEFAULT)),
                
                // Username in green bold
                new TerminalString(user, 
                        new TerminalColor(Color.GREEN, Color.DEFAULT),
                        CharacterType.BOLD),
                
                // @ symbol
                new TerminalString("@", 
                        new TerminalColor(Color.WHITE, Color.DEFAULT)),
                
                // Hostname in cyan
                new TerminalString("localhost", 
                        new TerminalColor(Color.CYAN, Color.DEFAULT)),
                
                // Space and directory in blue
                new TerminalString(" " + shortenPath(directory), 
                        new TerminalColor(Color.BLUE, Color.DEFAULT)),
                
                // Closing bracket and prompt symbol
                new TerminalString("]$ ", 
                        new TerminalColor(Color.WHITE, Color.DEFAULT))
        );
        
        return new Prompt(parts);
    }
    
    private static String shortenPath(String path) {
        // Replace home directory with ~
        String home = System.getProperty("user.home");
        if (path.startsWith(home)) {
            return "~" + path.substring(home.length());
        }
        return path;
    }
}

Git-Style Prompt

Create a prompt that shows git branch information:

public class GitPrompt {
    
    public Prompt create() {
        String branch = getGitBranch();
        String directory = getCurrentDirectory();
        
        List<TerminalString> parts = new ArrayList<>();
        
        // Directory in blue
        parts.add(new TerminalString(directory + " ", 
                new TerminalColor(Color.BLUE, Color.DEFAULT)));
        
        // Git branch if available
        if (branch != null) {
            parts.add(new TerminalString("(", Color.DEFAULT));
            parts.add(new TerminalString(branch, 
                    new TerminalColor(Color.MAGENTA, Color.DEFAULT)));
            parts.add(new TerminalString(") ", Color.DEFAULT));
        }
        
        // Prompt symbol
        parts.add(new TerminalString("$ ", Color.DEFAULT));
        
        return new Prompt(parts);
    }
    
    private String getGitBranch() {
        try {
            Process process = Runtime.getRuntime()
                    .exec(new String[]{"git", "branch", "--show-current"});
            BufferedReader reader = new BufferedReader(
                    new InputStreamReader(process.getInputStream()));
            String branch = reader.readLine();
            process.waitFor();
            return process.exitValue() == 0 ? branch : null;
        } catch (Exception e) {
            return null;
        }
    }
    
    private String getCurrentDirectory() {
        return System.getProperty("user.dir");
    }
}

Best Practices

  1. Keep prompts short - Long prompts reduce the space available for user input.

  2. Use colors meaningfully - Use colors to convey information (e.g., green for normal, red for root).

  3. Always mask passwords - Never echo password input to the terminal.

  4. Test color fallbacks - Ensure prompts are readable when colors are not supported.

  5. Consider accessibility - Don’t rely solely on color to convey information.

// Good: Information conveyed by text AND color
new TerminalString("[admin]# ", new TerminalColor(Color.RED, Color.DEFAULT))

// Bad: Information only conveyed by color
new TerminalString("$ ", new TerminalColor(Color.RED, Color.DEFAULT))
  1. Use dynamic prompts sparingly - Regenerating complex prompts on every input can impact performance.
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