Add ability to send posix/ansi signals in SshCommand

src/Renci.SshNet/CommandSignals.cs

@@ -0,0 +1,73 @@
+namespace Renci.SshNet
+{
+    /// <summary>
+    /// The ssh compatible standard POSIX/ANSI signals.
+    /// </summary>
+    public static class CommandSignals
+    {
+        /// <summary>
+        /// Hangup (POSIX).
+        /// </summary>
+        public const string SIGHUP = "HUP";
+
+        /// <summary>
+        /// Interrupt (ANSI).
+        /// </summary>
+        public const string SIGINT = "INT";
+
+        /// <summary>
+        /// Quit (POSIX).
+        /// </summary>
+        public const string SIGQUIT = "QUIT";
+
+        /// <summary>
+        /// Illegal instruction (ANSI).
+        /// </summary>
+        public const string SIGILL = "ILL";
+
+        /// <summary>
+        /// Abort (ANSI).
+        /// </summary>
+        public const string SIGABRT = "ABRT";
+
+        /// <summary>
+        /// Floating-point exception (ANSI).
+        /// </summary>
+        public const string SIGFPE = "FPE";
+
+        /// <summary>
+        /// Kill, unblockable (POSIX).
+        /// </summary>
+        public const string SIGKILL = "KILL";
+
+        /// <summary>
+        /// User-defined signal 1 (POSIX).
+        /// </summary>
+        public const string SIGUSR1 = "USR1";
+
+        /// <summary>
+        /// Segmentation violation (ANSI).
+        /// </summary>
+        public const string SIGSEGV = "SEGV";
+
+        /// <summary>
+        /// User-defined signal 2 (POSIX).
+        /// </summary>
+        public const string SIGUSR2 = "USR2";
+
+        /// <summary>
+        /// Broken pipe (POSIX).
+        /// </summary>
+        public const string SIGPIPE = "PIPE";
+
+        /// <summary>
+        /// Alarm clock (POSIX).
+        /// </summary>
+        public const string SIGALRM = "ALRM";
+
+        /// <summary>
+        /// Termination (ANSI).
+        /// </summary>
+        public const string SIGTERM = "TERM";
+    }
+}

src/Renci.SshNet/SshCommand.cs

@@ -478,6 +478,61 @@ public void CancelAsync(bool forceKill = false, int millisecondsTimeout = 500)
             }
         }
 
+        /// <summary>
+        /// Tries to send a POSIX/ANSI signal to the remote process executing the command, such as SIGTERM or any of the <see cref="CommandSignals"/>.
+        /// </summary>
+        /// <param name="signal">The signal to send. See <see cref="CommandSignals"/> for a standard list of signals.</param>
+        /// <returns>If the signal was sent.</returns>
+        public bool TrySendSignal(string signal)
+        {
+            if (signal is null)
+            {
+                return false;
+            }
+
+            if (_tcs is null || _tcs.Task.IsCompleted || _channel?.IsOpen != true)
+            {
+                return false;
+            }
+
+            try
+            {
+                // Try to send the cancellation signal.
+                return _channel.SendSignalRequest(signal);
+            }
+            catch (Exception)
+            {
+                // Exception can be ignored since we are in a Try method
+                // Possible exceptions here: InvalidOperationException, SshConnectionException, SshOperationTimeoutException
+            }
+
+            return false;
+        }
+
+        /// <summary>
+        /// Tries to send a POSIX/ANSI signal to the remote process executing the command, such as SIGTERM or any of the <see cref="CommandSignals"/>.
+        /// </summary>
+        /// <param name="signal">The signal to send. See <see cref="CommandSignals"/> for a standard list of signals.</param>
+        /// <exception cref="ArgumentException">Signal was not a valid CommandSignal.</exception>
+        /// <exception cref="SshConnectionException">The client is not connected.</exception>
+        /// <exception cref="SshOperationTimeoutException">The operation timed out.</exception>
+        /// <exception cref="InvalidOperationException">The size of the packet exceeds the maximum size defined by the protocol.</exception>
+        /// <exception cref="InvalidOperationException">Command has not been started.</exception>
+        public void SendSignal(string signal)
+        {
+            if (signal is null)
+            {
+                throw new ArgumentException("Signal was not a valid CommandSignal.");
+            }
+
+            if (_tcs is null || _tcs.Task.IsCompleted || _channel?.IsOpen != true)
+            {
+                throw new InvalidOperationException("Command has not been started.");
+            }
+
+            _ = _channel.SendSignalRequest(signal);
+        }
+
         /// <summary>
         /// Executes the command specified by <see cref="CommandText"/>.
         /// </summary>