Package org.jline.terminal

Interface Terminal.SignalHandler

All Known Implementing Classes:

NativeSignalHandler

Enclosing interface:

Terminal

public static interface Terminal.SignalHandler

Interface for handling terminal signals.

The SignalHandler interface defines the contract for objects that can respond to terminal signals. When a signal is raised, the corresponding handler's handle(Signal) method is called with the signal that was raised.

JLine provides two predefined signal handlers:

• SIG_DFL - Default signal handler that uses the JVM's default behavior
• SIG_IGN - Ignores the signal and performs no special processing

Example usage with a custom handler:

 Terminal terminal = TerminalBuilder.terminal();

 // Create a custom signal handler
 SignalHandler handler = signal -> {
     if (signal == Signal.INT) {
         terminal.writer().println("\nInterrupted!");
         terminal.flush();
     }
 };

 // Register the handler for the INT signal
 terminal.handle(Signal.INT, handler);
 

See Also:

• Terminal.Signal
• Terminal.handle(Signal, SignalHandler)

Field Summary

Fields

Modifier and Type	Field	Description
static final Terminal.SignalHandler	SIG_DFL	Default signal handler that uses the JVM's default behavior for the signal.
static final Terminal.SignalHandler	SIG_IGN	Signal handler that ignores the signal and performs no special processing.

Method Summary

Modifier and Type	Method	Description
void	handle(Terminal.Signal signal)	Handles the specified signal.

Field Details

SIG_DFL

static final Terminal.SignalHandler SIG_DFL

Default signal handler that uses the JVM's default behavior for the signal.

When this handler is registered for a signal, the terminal will use the JVM's default behavior to handle the signal. For example, the default behavior for the INT signal (Ctrl+C) is to terminate the JVM.

Example usage:

 // Restore default behavior for INT signal
 terminal.handle(Signal.INT, SignalHandler.SIG_DFL);
 

SIG_IGN

static final Terminal.SignalHandler SIG_IGN

Signal handler that ignores the signal and performs no special processing.

When this handler is registered for a signal, the terminal will completely ignore the signal and continue normal operation. This is useful for preventing signals like INT (Ctrl+C) from terminating the application.

Example usage:

 // Ignore INT signal (Ctrl+C will not terminate the application)
 terminal.handle(Signal.INT, SignalHandler.SIG_IGN);
 

Method Details

handle

void handle(Terminal.Signal signal)

Handles the specified signal.

This method is called when a signal is raised and this handler is registered for that signal. Implementations should perform any necessary actions in response to the signal.

Note that signal handlers should generally be short-lived and avoid blocking operations, as they may be called in contexts where blocking could cause deadlocks or other issues.

Parameters:

signal - the signal that was raised