nm 命令

最好是閱讀 man nm

nm - list symbols from object files

If lowercase, the symbol is local; if uppercase, the symbol is global (external)

其輸出結果：

  "A" The symbol’s value is absolute, and will not be changed by further linking.

  "B"/"b" The symbol is in the uninitialized data section (known as BSS).

   "C" The symbol is common.  Common symbols are uninitialized data.  When linking, multiple common symbols may appear with the same name.  If the symbol is defined anywhere, the common symbols are treated as undefined references.

"D"/"d" The symbol is in the initialized data section.

 "T"/"t" The symbol is in the text (code) section.

"U" The symbol is undefined.

"u" The symbol is a unique global symbol.  This is a GNU extension to the standard set of ELF symbol bindings.  For such a symbol the dynamic linker will make sure that in the entire process there is just one symbol with this name and type in use.

"S"/"s" The symbol is in an uninitialized data section for small objects.

A	Global absolute 符號。
a	Local absolute 符號。
B	Global bss 符號。
b	Local bss 符號。
D	Global data 符號。
d	Local data 符號。
f	源文件名稱符號。
T	Global text 符號。
t	Local text 符號。
U	未定義符號。