Module org.jline.terminal
Package org.jline.terminal.impl

Class AbstractUnixSysTerminal

java.lang.Object
org.jline.terminal.impl.AbstractTerminal
org.jline.terminal.impl.AbstractUnixSysTerminal
All Implemented Interfaces:
Closeable, Flushable, AutoCloseable, Sized, TerminalExt, Terminal
public abstract class AbstractUnixSysTerminal extends AbstractTerminal
Base class for flattened POSIX system terminals that bypass the PTY abstraction.

Subclasses only need to implement four methods for platform-specific attribute and size operations:

The call chain is reduced from 7 layers to 4:

   Terminal ? AbstractTerminal ? AbstractUnixSysTerminal ? subclass ? native call

Important: the underlying system streams (FileDescriptor.in, FileDescriptor.out/err) are wrapped in NonCloseableInputStream / NonCloseableOutputStream. Closing the terminal will shut down the pump thread and release resources, but will not close the shared file descriptors. This prevents breaking System.in/System.out for the rest of the JVM.

  • Field Details

  • Constructor Details

  • Method Details

    • handle

      public Terminal.SignalHandler handle(Terminal.Signal signal, Terminal.SignalHandler handler)
      Description copied from interface: Terminal
      Registers a handler for the given Terminal.Signal.

      This method allows the application to specify custom behavior when a particular signal is raised. The handler's Terminal.SignalHandler.handle(Signal) method will be called whenever the specified signal is raised.

      Note that the JVM does not easily allow catching the Terminal.Signal.QUIT signal (Ctrl+\), which typically causes a thread dump to be displayed. This signal handling is mainly effective when connecting through an SSH socket to a virtual terminal.

      Example usage:

       Terminal terminal = TerminalBuilder.terminal();

 // Handle window resize events
 terminal.handle(Signal.WINCH, signal -> {
     Size size = terminal.getSize();
     terminal.writer().println("\nTerminal resized to " +
                              size.getColumns() + "x" + size.getRows());
     terminal.flush();
 });

 // Ignore interrupt signal
 terminal.handle(Signal.INT, SignalHandler.SIG_IGN);
      Specified by:
      handle in interface Terminal
      Overrides:
      handle in class AbstractTerminal
      Parameters:
      signal - the signal to register a handler for
      handler - the handler to be called when the signal is raised
      Returns:
      the previous signal handler that was registered for this signal
      See Also:

    • doGetAttributes

      protected abstract Attributes doGetAttributes()

    • doSetAttributes

      protected abstract void doSetAttributes(Attributes attr)

    • doGetSize

      protected abstract Size doGetSize()

    • doSetSize

      protected abstract void doSetSize(Sized size)

    • getAttributes

      public Attributes getAttributes()
      Description copied from interface: Terminal
      Returns the current terminal attributes.

      Terminal attributes control various aspects of terminal behavior, including:

      • Input processing - How input characters are processed (e.g., character mapping, parity checking)
      • Output processing - How output characters are processed (e.g., newline translation)
      • Control settings - Hardware settings like baud rate and character size
      • Local settings - Terminal behavior settings like echo, canonical mode, and signal generation
      • Control characters - Special characters like EOF, interrupt, and erase

      The returned Attributes object is a copy of the terminal's current attributes and can be safely modified without affecting the terminal until it is applied using Terminal.setAttributes(Attributes). This allows for making multiple changes to the attributes before applying them all at once.

      Example usage:

       Terminal terminal = TerminalBuilder.terminal();

 // Get current attributes
 Attributes attrs = terminal.getAttributes();

 // Modify attributes
 attrs.setLocalFlag(LocalFlag.ECHO, false);      // Disable echo
 attrs.setInputFlag(InputFlag.ICRNL, false);     // Disable CR to NL mapping
 attrs.setControlChar(ControlChar.VMIN, 1);      // Set minimum input to 1 character
 attrs.setControlChar(ControlChar.VTIME, 0);     // Set timeout to 0 deciseconds

 // Apply modified attributes
 terminal.setAttributes(attrs);
      Returns:
      a copy of the terminal's current attributes
      See Also:

    • setAttributes

      public void setAttributes(Attributes attr)
      Description copied from interface: Terminal
      Sets the terminal attributes to the specified values.

      This method applies the specified attributes to the terminal, changing its behavior according to the settings in the Attributes object. The terminal makes a copy of the provided attributes, so further modifications to the attr object will not affect the terminal until this method is called again.

      Terminal attributes control various aspects of terminal behavior, including input and output processing, control settings, local settings, and special control characters. Changing these attributes allows for fine-grained control over how the terminal processes input and output.

      Common attribute modifications include:

      • Disabling echo for password input
      • Enabling/disabling canonical mode for line-by-line or character-by-character input
      • Disabling signal generation for custom handling of Ctrl+C and other control sequences
      • Changing control characters like the interrupt character or end-of-file character

      For convenience, the Terminal.enterRawMode() method provides a pre-configured set of attributes suitable for full-screen interactive applications.

      Example usage:

       Terminal terminal = TerminalBuilder.terminal();

 // Save original attributes for later restoration
 Attributes originalAttrs = terminal.getAttributes();

 try {
     // Create and configure new attributes
     Attributes attrs = new Attributes(originalAttrs);
     attrs.setLocalFlag(LocalFlag.ECHO, false);      // Disable echo for password input
     attrs.setLocalFlag(LocalFlag.ICANON, false);    // Disable canonical mode

     // Apply the new attributes
     terminal.setAttributes(attrs);

     // Use terminal with modified attributes...
 } finally {
     // Restore original attributes
     terminal.setAttributes(originalAttrs);
 }
      Parameters:
      attr - the attributes to apply to the terminal
      See Also:

    • getSize

      public Size getSize()
      Description copied from interface: Terminal
      Retrieve the size of the visible window
      Returns:
      the visible terminal size
      See Also:

    • setSize

      public void setSize(Sized size)
      Description copied from interface: Terminal
      Requests that the terminal adopt the specified window dimensions. Implementations may apply constraints or ignore the request if resizing is unsupported; callers should use Terminal.getSize() to observe the effective size after calling this method.
      Parameters:
      size - the desired terminal size (columns and rows)
      See Also:

    • reader

      public NonBlockingReader reader()
      Description copied from interface: Terminal
      Retrieve the Reader for this terminal. This is the standard way to read input from this terminal. The reader is non blocking.

      The returned reader is owned by this terminal and will be closed when the terminal is closed. Callers should not close it directly.

      Returns:
      The non blocking reader

    • writer

      public PrintWriter writer()
      Description copied from interface: Terminal
      Retrieve the Writer for this terminal. This is the standard way to write to this terminal.

      The returned writer is owned by this terminal and will be closed when the terminal is closed. Callers should not close it directly.

      Returns:
      The writer

    • input

      public InputStream input()
      Description copied from interface: Terminal
      Retrieve the input stream for this terminal. In some rare cases, there may be a need to access the terminal input stream directly. In the usual cases, use the Terminal.reader() instead.

      The returned stream is owned by this terminal and will be closed when the terminal is closed. Callers should not close it directly.

      Returns:
      The input stream
      See Also:

    • output

      public OutputStream output()
      Description copied from interface: Terminal
      Retrieve the output stream for this terminal. In some rare cases, there may be a need to access the terminal output stream directly. In the usual cases, use the Terminal.writer() instead.

      The returned stream is owned by this terminal and will be closed when the terminal is closed. Callers should not close it directly.

      Returns:
      The output stream
      See Also:

    • getProvider

      public TerminalProvider getProvider()
      Description copied from interface: TerminalExt
      Returns the terminal provider that created this terminal.

      The terminal provider is responsible for creating and managing terminal instances on a specific platform. This method allows access to the provider that created this terminal, which can be useful for accessing provider-specific functionality or for creating additional terminals with the same provider.

      Returns:
      the TerminalProvider that created this terminal, or null if the terminal was created with no provider
      See Also:

    • getSystemStream

      public SystemStream getSystemStream()
      Description copied from interface: TerminalExt
      Returns the system stream associated with this terminal, if any.

      This method indicates whether the terminal is bound to a standard system stream (standard input, standard output, or standard error). Terminals that are connected to system streams typically represent the actual terminal window or console that the application is running in.

      Returns:
      the underlying system stream, which may be SystemStream.Input, SystemStream.Output, SystemStream.Error, or null if this terminal is not bound to a system stream
      See Also:

    • getCursorPosition

      public Cursor getCursorPosition(IntConsumer discarded)
      Description copied from interface: Terminal
      Query the terminal to report the cursor position. As the response is read from the input stream, some characters may be read before the cursor position is actually read. Those characters can be given back using org.jline.keymap.BindingReader#runMacro(String)
      Specified by:
      getCursorPosition in interface Terminal
      Overrides:
      getCursorPosition in class AbstractTerminal
      Parameters:
      discarded - a consumer receiving discarded characters
      Returns:
      null if cursor position reporting is not supported or a valid cursor position

    • doClose

      protected void doClose() throws IOException
      Overrides:
      doClose in class AbstractTerminal
      Throws:
      IOException

    • getDefaultForegroundColor

      public int getDefaultForegroundColor()
      Description copied from class: AbstractTerminal
      Get the terminal's default foreground color. This method should be overridden by concrete implementations.
      Specified by:
      getDefaultForegroundColor in interface Terminal
      Overrides:
      getDefaultForegroundColor in class AbstractTerminal
      Returns:
      the RGB value of the default foreground color, or -1 if not available
      See Also:

    • getDefaultBackgroundColor

      public int getDefaultBackgroundColor()
      Description copied from class: AbstractTerminal
      Get the terminal's default background color. This method should be overridden by concrete implementations.
      Specified by:
      getDefaultBackgroundColor in interface Terminal
      Overrides:
      getDefaultBackgroundColor in class AbstractTerminal
      Returns:
      the RGB value of the default background color, or -1 if not available
      See Also:

    • toString

      public String toString()
      Overrides:
      toString in class AbstractTerminal