Class TtyDetect

java.lang.Object
org.aesh.terminal.tty.TtyDetect
public final class TtyDetect extends Object
Utility for detecting whether file descriptors are connected to a terminal.

On Java 22+, uses FFM to call POSIX isatty() for accurate per-fd detection. On older Java versions, falls back to System.console() and Console.isTerminal() (Java 22+) as heuristics.

Typical usage: 

if (TtyDetect.isStdinTty()) {
    // Interactive mode — show prompt, enable completion
} else {
    // Piped/redirected — read commands from stdin
}

if (!TtyDetect.isStdoutTty()) {
    // Output is piped — disable colors, use machine-readable format
}

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    FD_STDERR
    File descriptor for standard error.
    static final int
    FD_STDIN
    File descriptor for standard input.
    static final int
    FD_STDOUT
    File descriptor for standard output.

  • Method Summary

    Modifier and Type
    Method
    Description
    static boolean
    isStderrTty()
    Check if standard error is connected to a terminal.
    static boolean
    isStdinTty()
    Check if standard input is connected to a terminal.
    static boolean
    isStdoutTty()
    Check if standard output is connected to a terminal.
    static boolean
    isTty(int fd)
    Check if the given file descriptor is connected to a terminal.

    Methods inherited from class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • FD_STDIN

      public static final int FD_STDIN
      File descriptor for standard input.
      See Also:

    • FD_STDOUT

      public static final int FD_STDOUT
      File descriptor for standard output.
      See Also:

    • FD_STDERR

      public static final int FD_STDERR
      File descriptor for standard error.
      See Also:

  • Method Details

    • isTty

      public static boolean isTty(int fd)
      Check if the given file descriptor is connected to a terminal.

      On Java 22+ with POSIX systems, this uses the native isatty() function via FFM for accurate detection. On older Java versions or unsupported platforms, falls back to heuristics based on System.console().

      Parameters:
      fd - the file descriptor (0=stdin, 1=stdout, 2=stderr)
      Returns:
      true if the file descriptor is connected to a terminal

    • isStdinTty

      public static boolean isStdinTty()
      Check if standard input is connected to a terminal. Result is cached after the first call.
      Returns:
      true if stdin is a terminal (interactive input)

    • isStdoutTty

      public static boolean isStdoutTty()
      Check if standard output is connected to a terminal. Result is cached after the first call.
      Returns:
      true if stdout is a terminal (not piped/redirected)

    • isStderrTty

      public static boolean isStderrTty()
      Check if standard error is connected to a terminal. Result is cached after the first call.
      Returns:
      true if stderr is a terminal (not piped/redirected)