added some useless shell commands

programs/rocksh/main.c

@@ -1,13 +1,46 @@
 #include <unistd.h>
 #include <stdio.h>
+#include <string.h>
 
 const char* shell_prompt = "rocksh> ";
 
+char buf[256];
+size_t buf_offset = 0;
+
+void parse_cmd() {
+    if (strcmp(buf, "exit") == 0) {
+        printf("bye!\n");
+        exit(0);
+    }
+
+    if (strcmp(buf, "motd")  == 0) {
+        printf("rockos is the best!\n");
+    }
+}
+
+void reset() {
+    memset(buf, 0, 256);
+    buf_offset = 0;
+}
+
 int main(int argc, char *argv[]) {
     (void)argc;
     (void)argv;
 
     printf(shell_prompt);
+    while (1) {
+        char c;
+        int rd = read(0, &c, 1);
+        if (rd > 0) {
+            if (c == '\n') {
+                parse_cmd();
+                reset();
+                printf(shell_prompt);
+                continue;
+            }
+            buf[buf_offset++] = c;
+        }
+    }
 
     return 0;
 }