diff --git a/.vscode/settings.json b/.vscode/settings.json
index abc8474..d098913 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -5,5 +5,12 @@
         "loop.h": "c",
         "exec.h": "c"
     },
-    "editor.tabSize": 2
+    "editor.tabSize": 2,
+    "makefile.launchConfigurations": [
+        {
+            "cwd": "/home/ir/dev/priCode/dish",
+            "binaryPath": "/home/ir/dev/priCode/dish/dish",
+            "binaryArgs": []
+        }
+    ]
 }
\ No newline at end of file
diff --git a/Makefile b/Makefile
index 17d7032..99c6dfd 100644
--- a/Makefile
+++ b/Makefile
@@ -2,16 +2,21 @@ OBJ=main.o line.o loop.o exec.o
 CC=gcc
 CFLAGS= -O3 -Wall
 
-all:debug
-
+all:release
+r:release
 release:dish
 
 dish: $(OBJ)
 	$(CC) $(CFLAGS) -o dish $(OBJ)
 
+d: 
+	make clean
+	make debug
+
 debug: CFLAGS += -DDEBUG -g
 debug: dish
 
+c: clean
 clean:
 	rm -f $(OBJ) dish
 
diff --git a/exec.c b/exec.c
new file mode 100644
index 0000000..aa1d644
--- /dev/null
+++ b/exec.c
@@ -0,0 +1,28 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+int forkExec(char **args) {
+  pid_t pid;
+  int status;
+#ifdef DEBUG
+    printf("debug: fork enter.\n");
+#endif
+  pid = fork();
+  if (pid == 0) { 
+    /* child process */
+      if (execvp(args[0], args) == -1) {
+        perror("dish");
+        exit(EXIT_FAILURE);
+      }
+  } else if (pid < 0) {
+    /* fork error */
+    perror("dish");
+  } else {
+    /* parent process: wait child process*/
+    pid=wait(&status);
+    
+  }
+  return WEXITSTATUS(status);
+}
diff --git a/exec.h b/exec.h
new file mode 100644
index 0000000..8b7f0ce
--- /dev/null
+++ b/exec.h
@@ -0,0 +1,4 @@
+#ifndef __EXEC_H__
+#define __EXEC_H__
+int forkExec(char **args);
+#endif
\ No newline at end of file
diff --git a/line.c b/line.c
index 16eef5c..0733a50 100644
--- a/line.c
+++ b/line.c
@@ -17,7 +17,6 @@ char *readLine(void) {
   while (1) {
     // read a character
     c = getchar();
-    printf("%s", &c);
     // repleace EOF with a null character and return
     if (c == EOF || c == '\n') {
       buffer[position] = '\0';
diff --git a/main.c b/main.c
index 63696bd..7ca5c56 100644
--- a/main.c
+++ b/main.c
@@ -5,7 +5,7 @@
 #include "loop.h"
 
 void intHandler(int dummy) {
-  printf("\nend!\n");
+  printf("\nSIGINT exit.\n");
   exit(EXIT_FAILURE);
 }
 
@@ -13,7 +13,6 @@ int main(int argc, char *argv[]) {
 
   signal(SIGINT, intHandler);
 
-  printf("Hello, World!\n");
 #ifdef DEBUG
   printf("DEBUG is defined\n");
 #endif