shell can launch another user processgit add .git add .!

rocklibc/include/syscall.h

@@ -13,7 +13,8 @@
 #define SYS_FORK    21
 #define SYS_EXEC    22
 #define SYS_DUP2    23
-#define SYS_LSEEK    24
+#define SYS_LSEEK   24
+#define SYS_WAIT    25
 
 int open(const char* path);
 int write(int fd, const void *buf, size_t count);
@@ -32,5 +33,6 @@ int pty(int* slave);
 int fork();
 int exec(const char* path);
 int dup2(int src, int dst);
+int waitpid(int pid, int* status);
 
 #endif

rocklibc/src/syscall.c

@@ -61,4 +61,8 @@ int exec(const char* path) {
 
 int dup2(int src, int dst) {
     return syscall3(SYS_DUP2, src, dst, 0);
+}
+
+int waitpid(int pid, int* status) {
+    return syscall3(SYS_WAIT, pid, (uint32_t)status, 0);
 }