diff --git a/src/internal.cpp b/src/internal.cpp
index 2fefc58..e44032c 100644
--- a/src/internal.cpp
+++ b/src/internal.cpp
@@ -1,11 +1,13 @@
 #include "internal.h"
 #include <sys/shm.h>
+#include <csignal>
+
 Impl impl;
 
 void *getSharedMemory(){
     impl.sharedMemorySize = 8000;
 
-    auto id = shmget(impl.sharedMemoryKey, impl.sharedMemorySize, 0644 | IPC_CREAT);
+    auto id = shmget(impl.sharedMemoryKey, impl.sharedMemorySize, 0644u | IPC_CREAT);
     if(id == -1){
         //error
         impl.sharedMemorySize = 0;
@@ -25,3 +27,11 @@ void *getSharedMemory(){
 int getSharedMemorySize(){
     return impl.sharedMemorySize;
 }
+
+void sendSignal(pid_t pid, int signalNumber) {
+    kill(pid, signalNumber);
+}
+
+void onSignal(int signalNumber, void(*callback)(int)) {
+    signal(signalNumber, callback);
+}
diff --git a/src/internal.h b/src/internal.h
index 831ad27..2365c6e 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -54,6 +54,19 @@ void *getSharedMemory();
 
 int getSharedMemorySize();
 
+/**
+ * send a signal to a process
+ * @param pid of the process to which the signal is send
+ * @param signalNumber
+ */
+void sendSignal(pid_t pid, int signalNumber);
+
+/**
+ * calls the callback if a signal is received
+ * @param signalNumber
+ */
+void onSignal(int signalNumber, void(*callback)(int));
+
 /**
  * set layout version.
  * @param newValue new layout version number.