9 files changed, 48 insertions, 18 deletions
diff --git a/src/command/cd.cc b/src/command/cd.cc
index 49b1899..5434f20 100644
--- a/src/command/cd.cc
+++ b/src/command/cd.cc
@@ -1,10 +1,32 @@
 #include "command/builtin.h"
 
-namespace ov4::command
-{
+#include <cerrno>
+#include <unordered_map>
 
 using namespace std;
 
+// constexpr string_view
+//     err_EACCES = "cd: Search permission is denied for one of the components of path.",
+//     err_EFAULT = "cd: path points outside your accessible address space.",
+//     err_EIO = "An I/O error occurred.",
+//     err_ENOTDIR = "A component of path is not a directory.",
+//     err_ENOENT = "The directory specified in path does not exist.",
+//     err_ENAMETOOLONG = "path is too long.",
+//     err_ENOMEM = "Insufficient kernel memory was available.";
+
+const unordered_map<int, string_view> err_list = {
+    { EACCES, "cd: Search permission is denied for one of the components of path." },
+    { EFAULT, "cd: path points outside your accessible address space." },
+    { EIO, "An I/O error occurred." },
+    { ENOTDIR, "A component of path is not a directory." },
+    { ENOENT, "The directory specified in path does not exist." },
+    { ENAMETOOLONG, "path is too long." },
+    { ENOMEM, "Insufficient kernel memory was available."},
+};
+
+namespace ov4::command
+{
+
 void cd(char **argv)
 {
     if (argv == nullptr) return;
@@ -13,7 +35,16 @@ void cd(char **argv)
         cout << "cd: requires path" << endl;
         return;
     }
-    ov4::set_current_dir(argv[1]);
+    int ret = ov4::set_current_dir(argv[1]);
+    if (ret != 0)
+    {
+        if (err_list.find(errno) != err_list.end())
+        {
+            cout << "cd: " << err_list.at(errno) << endl;
+            return;
+        }
+        cout << "cd: Error occured, code: " << errno << endl;
+    }
 }
 
 }
diff --git a/src/eval.cc b/src/eval.cc
index b700c21..4f293c7 100644
--- a/src/eval.cc
+++ b/src/eval.cc
@@ -1,10 +1,10 @@
 #include "eval.h"
 
-namespace ov4
-{
-
 using namespace std;
 
+namespace ov4
+{
+    
 /* 
  * eval - Evaluate the command line that the user has just typed in
  * 
diff --git a/src/global.cc b/src/global.cc
index 0995b4d..e2a17ab 100644
--- a/src/global.cc
+++ b/src/global.cc
@@ -3,8 +3,6 @@
 namespace ov4
 {
 
-using namespace std;
-
 int verbose = 0;
 
 }
diff --git a/src/ground.cc b/src/ground.cc
index 2047ebf..54a333f 100644
--- a/src/ground.cc
+++ b/src/ground.cc
@@ -1,10 +1,10 @@
 #include "ground.h"
 
+using namespace std;
+
 namespace ov4
 {
 
-using namespace std;
-
 /* 
  * waitfg - Block until process pid is no longer the foreground process
  */
diff --git a/src/init.cc b/src/init.cc
index e4d0b8f..5f6e325 100644
--- a/src/init.cc
+++ b/src/init.cc
@@ -1,10 +1,10 @@
 #include "init.h"
 
+using namespace std;
+
 namespace ov4
 {
 
-using namespace std;
-
 void init()
 {
     cout << "\
diff --git a/src/path.cc b/src/path.cc
index 4d2ea1b..6feabee 100644
--- a/src/path.cc
+++ b/src/path.cc
@@ -39,7 +39,7 @@ string find_cmd(const string &s)
     }
 }
 
-string path_unifier(const string &s)
+string path_unifier(const string &s, bool is_cmd)
 {
     if (s.size() == 0) return "";
     if (s[0] == '/') return s;
diff --git a/src/util/io.cc b/src/util/io.cc
index 1261684..4a094d0 100644
--- a/src/util/io.cc
+++ b/src/util/io.cc
@@ -1,10 +1,10 @@
 #include "util/io.h"
 
+using namespace std;
+
 namespace ov4
 {
 
-using namespace std;
-
 void atomic_print(char *s, bool ignore_wrap)
 {
     if (ignore_wrap)
diff --git a/src/util/prompt.cc b/src/util/prompt.cc
index 977cb0b..ac9137b 100644
--- a/src/util/prompt.cc
+++ b/src/util/prompt.cc
@@ -1,8 +1,9 @@
 #include "util/prompt.h"
 
+using namespace std;
+
 namespace ov4
 {
-    using namespace std;
 
     bool emit_prompt = true; /* emit prompt (default) */
 
diff --git a/src/util/string.cc b/src/util/string.cc
index 8c6c86a..7146fe3 100644
--- a/src/util/string.cc
+++ b/src/util/string.cc
@@ -1,10 +1,10 @@
 #include "util/string.h"
 
+using namespace std;
+
 namespace ov4
 {
 
-using namespace std;
-
 void string2argv(const vector<string> * const s, char **argv)
 {