diff --git a/examples/BuiltIn/seek.py b/examples/BuiltIn/seek.py
new file mode 100644
index 000000000..9e3efaf55
--- /dev/null
+++ b/examples/BuiltIn/seek.py
@@ -0,0 +1,4 @@
+f = open('test/assets/test.jpg', 'rb')
+len = f.seek(0, 2)
+print(len)
+f.close()
\ No newline at end of file
diff --git a/package/PikaStdLib/PikaStdData.pyi b/package/PikaStdLib/PikaStdData.pyi
index 649a7f095..aacfce77d 100644
--- a/package/PikaStdLib/PikaStdData.pyi
+++ b/package/PikaStdLib/PikaStdData.pyi
@@ -80,7 +80,7 @@ class String:
     def strip(self) -> str: ...
 
 
-class ByteArray(TinyObj):
+class ByteArray:
     # convert a string to ByteArray
     def __init__(self, bytes: any): ...
     # support for loop
@@ -97,8 +97,10 @@ class ByteArray(TinyObj):
 class FILEIO:
     def init(self, path: str, mode: str): ...
     def read(self, size: int) -> any: ...
-    def write(self, s: any): ...
+    def write(self, s: any) -> int: ...
     def close(self): ...
+    def seek(self, offset: int, *fromwhere) -> int: ...
+    def tell(self) -> int: ...
 
 
 class Utils:
diff --git a/package/PikaStdLib/PikaStdData_FILEIO.c b/package/PikaStdLib/PikaStdData_FILEIO.c
index 4c06ceda8..612f69cfe 100644
--- a/package/PikaStdLib/PikaStdData_FILEIO.c
+++ b/package/PikaStdLib/PikaStdData_FILEIO.c
@@ -55,20 +55,48 @@ Arg* PikaStdData_FILEIO_read(PikaObj* self, int size) {
     }
 }
 
-void PikaStdData_FILEIO_write(PikaObj* self, Arg* s) {
+int PikaStdData_FILEIO_write(PikaObj* self, Arg* s) {
     FILE* f = obj_getPtr(self, "_f");
+    int res = -1;
     if (f == NULL) {
         obj_setErrorCode(self, PIKA_RES_ERR_IO);
         __platform_printf("Error: can't write to file\n");
-        return;
+        return res;
     }
     char* mode = obj_getStr(self, "_mode");
     if (strIsContain(mode, 'b')) {
         /* binary */
-        __platform_fwrite(arg_getBytes(s), 1, arg_getSize(s), f);
+        res = __platform_fwrite(arg_getBytes(s), 1, arg_getSize(s), f);
     } else {
         /* text */
         char* str = arg_getStr(s);
-        __platform_fwrite(str, 1, strlen(str), f);
+        res = __platform_fwrite(str, 1, strlen(str), f);
     }
+    return res;
+}
+
+int PikaStdData_FILEIO_seek(PikaObj* self, PikaTuple* fromwhere, int offset) {
+    FILE* f = obj_getPtr(self, "_f");
+    if (f == NULL) {
+        obj_setErrorCode(self, PIKA_RES_ERR_IO);
+        __platform_printf("Error: can't seek in file\n");
+        return -1;
+    }
+    if (tuple_getSize(fromwhere) == 1) {
+        int whence = tuple_getInt(fromwhere, 0);
+        __platform_fseek(f, offset, whence);
+        return __platform_ftell(f);
+    }
+    __platform_fseek(f, offset, 0);
+    return __platform_ftell(f);
+}
+
+int PikaStdData_FILEIO_tell(PikaObj* self) {
+    FILE* f = obj_getPtr(self, "_f");
+    if (f == NULL) {
+        obj_setErrorCode(self, PIKA_RES_ERR_IO);
+        __platform_printf("Error: can't tell in file\n");
+        return -1;
+    }
+    return __platform_ftell(f);
 }
diff --git a/port/linux/package/pikascript/PikaStdData.pyi b/port/linux/package/pikascript/PikaStdData.pyi
index 649a7f095..aacfce77d 100644
--- a/port/linux/package/pikascript/PikaStdData.pyi
+++ b/port/linux/package/pikascript/PikaStdData.pyi
@@ -80,7 +80,7 @@ class String:
     def strip(self) -> str: ...
 
 
-class ByteArray(TinyObj):
+class ByteArray:
     # convert a string to ByteArray
     def __init__(self, bytes: any): ...
     # support for loop
@@ -97,8 +97,10 @@ class ByteArray(TinyObj):
 class FILEIO:
     def init(self, path: str, mode: str): ...
     def read(self, size: int) -> any: ...
-    def write(self, s: any): ...
+    def write(self, s: any) -> int: ...
     def close(self): ...
+    def seek(self, offset: int, *fromwhere) -> int: ...
+    def tell(self) -> int: ...
 
 
 class Utils:
diff --git a/port/linux/package/pikascript/pikascript-lib/PikaStdLib/PikaStdData_FILEIO.c b/port/linux/package/pikascript/pikascript-lib/PikaStdLib/PikaStdData_FILEIO.c
index 4c06ceda8..612f69cfe 100644
--- a/port/linux/package/pikascript/pikascript-lib/PikaStdLib/PikaStdData_FILEIO.c
+++ b/port/linux/package/pikascript/pikascript-lib/PikaStdLib/PikaStdData_FILEIO.c
@@ -55,20 +55,48 @@ Arg* PikaStdData_FILEIO_read(PikaObj* self, int size) {
     }
 }
 
-void PikaStdData_FILEIO_write(PikaObj* self, Arg* s) {
+int PikaStdData_FILEIO_write(PikaObj* self, Arg* s) {
     FILE* f = obj_getPtr(self, "_f");
+    int res = -1;
     if (f == NULL) {
         obj_setErrorCode(self, PIKA_RES_ERR_IO);
         __platform_printf("Error: can't write to file\n");
-        return;
+        return res;
     }
     char* mode = obj_getStr(self, "_mode");
     if (strIsContain(mode, 'b')) {
         /* binary */
-        __platform_fwrite(arg_getBytes(s), 1, arg_getSize(s), f);
+        res = __platform_fwrite(arg_getBytes(s), 1, arg_getSize(s), f);
     } else {
         /* text */
         char* str = arg_getStr(s);
-        __platform_fwrite(str, 1, strlen(str), f);
+        res = __platform_fwrite(str, 1, strlen(str), f);
     }
+    return res;
+}
+
+int PikaStdData_FILEIO_seek(PikaObj* self, PikaTuple* fromwhere, int offset) {
+    FILE* f = obj_getPtr(self, "_f");
+    if (f == NULL) {
+        obj_setErrorCode(self, PIKA_RES_ERR_IO);
+        __platform_printf("Error: can't seek in file\n");
+        return -1;
+    }
+    if (tuple_getSize(fromwhere) == 1) {
+        int whence = tuple_getInt(fromwhere, 0);
+        __platform_fseek(f, offset, whence);
+        return __platform_ftell(f);
+    }
+    __platform_fseek(f, offset, 0);
+    return __platform_ftell(f);
+}
+
+int PikaStdData_FILEIO_tell(PikaObj* self) {
+    FILE* f = obj_getPtr(self, "_f");
+    if (f == NULL) {
+        obj_setErrorCode(self, PIKA_RES_ERR_IO);
+        __platform_printf("Error: can't tell in file\n");
+        return -1;
+    }
+    return __platform_ftell(f);
 }
diff --git a/port/linux/test/builtin-test.cpp b/port/linux/test/builtin-test.cpp
index 80da9bf10..a4df94492 100644
--- a/port/linux/test/builtin-test.cpp
+++ b/port/linux/test/builtin-test.cpp
@@ -35,3 +35,21 @@ TEST(builtin, type1) {
     EXPECT_EQ(pikaMemNow(), 0);
 }
 #endif
+
+#if PIKA_SYNTAX_LEVEL == PIKA_SYNTAX_LEVEL_MAXIMAL
+TEST(builtin, seek) {
+    /* init */
+    pikaMemInfo.heapUsedMax = 0;
+    PikaObj* pikaMain = newRootObj("pikaMain", New_PikaMain);
+    /* run */
+    __platform_printf("BEGIN\r\n");
+    pikaVM_runSingleFile(pikaMain, "../../examples/BuiltIn/seek.py");
+    /* collect */
+    int len = obj_getInt(pikaMain, "len");
+    /* assert */
+    EXPECT_EQ(len, 3576);
+    /* deinit */
+    obj_deinit(pikaMain);
+    EXPECT_EQ(pikaMemNow(), 0);
+}
+#endif
diff --git a/src/PikaPlatform.c b/src/PikaPlatform.c
index 7f0d16e72..edc549182 100644
--- a/src/PikaPlatform.c
+++ b/src/PikaPlatform.c
@@ -101,6 +101,7 @@ PIKA_WEAK void __platform_wait(void) {
     while (1) {
     };
 }
+
 PIKA_WEAK void* __platform_memset(void* mem, int ch, size_t size) {
     return memset(mem, ch, size);
 }
@@ -119,6 +120,7 @@ PIKA_WEAK char __platform_getchar(void) {
 #endif
 }
 
+/* fopen */
 PIKA_WEAK FILE* __platform_fopen(const char* filename, const char* modes) {
 #if defined(__linux) || defined(_WIN32)
     return fopen(filename, modes);
@@ -129,6 +131,7 @@ PIKA_WEAK FILE* __platform_fopen(const char* filename, const char* modes) {
 #endif
 }
 
+/* fclose */
 PIKA_WEAK int __platform_fclose(FILE* stream) {
 #if defined(__linux) || defined(_WIN32)
     return fclose(stream);
@@ -139,6 +142,7 @@ PIKA_WEAK int __platform_fclose(FILE* stream) {
 #endif
 }
 
+/* fwrite */
 PIKA_WEAK size_t __platform_fwrite(const void* ptr,
                                    size_t size,
                                    size_t n,
@@ -152,6 +156,7 @@ PIKA_WEAK size_t __platform_fwrite(const void* ptr,
 #endif
 }
 
+/* fread */
 PIKA_WEAK size_t __platform_fread(void* ptr,
                                   size_t size,
                                   size_t n,
@@ -164,3 +169,25 @@ PIKA_WEAK size_t __platform_fread(void* ptr,
     }
 #endif
 }
+
+/* fseek */
+PIKA_WEAK int __platform_fseek(FILE* stream, long offset, int whence) {
+#if defined(__linux) || defined(_WIN32)
+    return fseek(stream, offset, whence);
+#else
+    __platform_printf("[error]: __platform_fseek need implementation!\r\n");
+    while (1) {
+    }
+#endif
+}
+
+/* ftell */
+PIKA_WEAK long __platform_ftell(FILE* stream) {
+#if defined(__linux) || defined(_WIN32)
+    return ftell(stream);
+#else
+    __platform_printf("[error]: __platform_ftell need implementation!\r\n");
+    while (1) {
+    }
+#endif
+}
diff --git a/src/PikaPlatform.h b/src/PikaPlatform.h
index 6c76453f8..0d33dc984 100644
--- a/src/PikaPlatform.h
+++ b/src/PikaPlatform.h
@@ -152,8 +152,10 @@ FILE* __platform_fopen(const char* filename, const char* modes);
 int __platform_fclose(FILE* stream);
 size_t __platform_fwrite(const void* ptr, size_t size, size_t n, FILE* stream);
 size_t __platform_fread(void* ptr, size_t size, size_t n, FILE* stream);
+int __platform_fseek(FILE* stream, long offset, int whence);
 
 /* error */
 void __platform_error_handle(void);
+long __platform_ftell(FILE* stream);
 
 #endif
diff --git a/src/PikaVersion.h b/src/PikaVersion.h
index 2f054827b..1a52af280 100644
--- a/src/PikaVersion.h
+++ b/src/PikaVersion.h
@@ -2,4 +2,4 @@
 #define PIKA_VERSION_MINOR       9
 #define PIKA_VERSION_MICRO       1
 
-#define PIKA_EDIT_TIME      "2022/07/15 10:48:23"
+#define PIKA_EDIT_TIME      "2022/07/18 13:14:40"
diff --git a/src/dataArgs.c b/src/dataArgs.c
index 6c76fb6c1..16bb6707d 100644
--- a/src/dataArgs.c
+++ b/src/dataArgs.c
@@ -551,6 +551,26 @@ Arg* list_getArg(PikaList* self, int index) {
     return args_getArg(&self->super, i_str);
 }
 
+int list_getInt(PikaList* self, int index) {
+    Arg* arg = list_getArg(self, index);
+    return arg_getInt(arg);
+}
+
+double list_getFloat(PikaList* self, int index) {
+    Arg* arg = list_getArg(self, index);
+    return arg_getFloat(arg);
+}
+
+char* list_getStr(PikaList* self, int index) {
+    Arg* arg = list_getArg(self, index);
+    return arg_getStr(arg);
+}
+
+void* list_getPtr(PikaList* self, int index) {
+    Arg* arg = list_getArg(self, index);
+    return arg_getPtr(arg);
+}
+
 PIKA_RES list_append(PikaList* self, Arg* arg) {
     int top = args_getInt(&self->super, "top");
     char buff[11];
diff --git a/src/dataArgs.h b/src/dataArgs.h
index 763e43c4a..96e830f4a 100644
--- a/src/dataArgs.h
+++ b/src/dataArgs.h
@@ -162,6 +162,10 @@ PikaDict* New_dict(void);
 #define list_deinit(self) (args_deinit((&((self)->super))))
 PIKA_RES list_append(PikaList* self, Arg* arg);
 PIKA_RES list_setArg(PikaList* self, int index, Arg* arg);
+int list_getInt(PikaList* self, int index);
+double list_getFloat(PikaList* self, int index);
+char* list_getStr(PikaList* self, int index);
+void* list_getPtr(PikaList* self, int index);
 Arg* list_getArg(PikaList* self, int index);
 size_t list_getSize(PikaList* self);
 char* strsFormatArg(Args* out_buffs, char* fmt, Arg* arg);
@@ -170,6 +174,12 @@ char* strsFormatArg(Args* out_buffs, char* fmt, Arg* arg);
 #define tuple_deinit(self) (list_deinit((&((self)->super))))
 #define tuple_getArg(self, index) (list_getArg((&((self)->super)), (index)))
 #define tuple_getSize(self) (list_getSize((&((self)->super))))
+#define tuple_getInt(self, index) (list_getInt((&((self)->super)), (index)))
+#define tuple_getFloat(self, index) \
+    (list_getFloat((&((self)->super)), (index)))
+#define tuple_getStr(self, index) (list_getStr((&((self)->super)), (index)))
+#define tuple_getPtr(self, index) (list_getPtr((&((self)->super)), (index)))
+#define tuple_getType(self, index) (list_getType((&((self)->super)), (index)))
 
 PikaList* New_list(void);
 PikaTuple* New_tuple(void);