How do I list the symbols in a so file

Question

How do I list the symbols being exported from a  so file   If possible  I d also like to know their source  e g  if they are pulled in from a static library    I m using gcc 4 0 2  if that makes a difference

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For C    so files  the ultimate nm command is nm --demangle --dynamic --defined-only --extern-only  lt my so gt     nm --demangle --dynamic --defined-only --extern-only  usr lib64 libqpid-proton-cpp so   grep work   grep add 0000000000049500 T proton  work queue  add proton  internal  v03  work  0000000000049580 T proton  work queue  add proton  void function0 amp   000000000002e7b0 W proton  work queue  impl  add void proton  internal  v03  work  000000000002b1f0 T proton  container  impl  add work queue   000000000002dc50 T proton  container  impl  container work queue  add proton  internal  v03  work  000000000002db60 T proton  container  impl  connection work queue  add proton  internal  v03  work    source  https   stackoverflow com a 43257338

User · Answer

If your  so file is in elf format  you can use readelf program to extract symbol information from the binary   This command will give you the symbol table   readelf -Ws  usr lib libexample so   You only should extract those that are defined in this  so file  not in the libraries referenced by it   Seventh column should contain a number in this case   You can extract it by using a simple regex   readelf -Ws  usr lib libstdc   so 6   grep        space         space         6     space        digit         or  as proposed by Caspin    readelf -Ws  usr lib libstdc   so 6   awk   print  8

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If you just want to know if there are symbols present you can use  objdump -h  path to object   or to list the debug info  objdump -g  path to object

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nm -g  list the extern variable  which is not necessary exported symbol  Any non-static file scope variable in C  are all extern variable   nm -D  will list the symbol in the dynamic table  which you can find it s address by dlsym   nm --version   GNU nm 2 17 50 0 6-12 el5 20061020

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The standard tool for listing symbols is nm  you can use it simply like this   nm -gD yourLib so   If you want to see symbols of a C   library  add the  -C  option which demangle the symbols  it s far more readable demangled    nm -gDC yourLib so   If your  so file is in elf format  you have two options   Either objdump  -C is also useful for demangling C        objdump -TC libz so  libz so      file format elf64-x86-64  DYNAMIC SYMBOL TABLE  0000000000002010 l    d   init  0000000000000000               init 0000000000000000      DF  UND   0000000000000000  GLIBC 2 2 5 free 0000000000000000      DF  UND   0000000000000000  GLIBC 2 2 5   errno location 0000000000000000  w   D   UND   0000000000000000               ITM deregisterTMCloneTable   Or use readelf     readelf -Ws libz so Symbol table   dynsym  contains 112 entries     Num     Value          Size Type    Bind   Vis      Ndx Name      0  0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND      1  0000000000002010     0 SECTION LOCAL  DEFAULT   10      2  0000000000000000     0 FUNC    GLOBAL DEFAULT  UND free GLIBC 2 2 5  14       3  0000000000000000     0 FUNC    GLOBAL DEFAULT  UND   errno location GLIBC 2 2 5  14       4  0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND  ITM deregisterTMCloneTable

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I kept wondering why -fvisibility hidden and  pragma GCC visibility did not seem to have any influence  as all the symbols were always visible with nm - until I found this post that pointed me to readelf and objdump  which made me realize that there seem to actually be two symbol tables    The one you can list with nm The one you can list with readelf and objdump   I think the former contains debugging symbols that can be stripped with strip or the -s switch that you can give to the linker or the install command  And even if nm does not list anything anymore  your exported symbols are still exported because they are in the ELF  dynamic symbol table   which is the latter

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For shared libraries libNAME so the -D switch was necessary to see symbols in my Linux  nm -D libNAME so   and for static library as reported by others  nm -g libNAME a

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objdump -TC  usr lib libexample so

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Try adding -l to the nm flags in order to get the source of each symbol   If the library is compiled with debugging info  gcc -g  this should be the source file and line number   As Konrad said  the object file   static library is probably unknown at this point

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For Android  so files  the NDK toolchain comes with the required tools mentioned in the other answers  readelf  objdump and nm

User · Answer

You can use the nm -g tool from the binutils toolchain  However  their source is not always readily available  and I m not actually even sure that this information can always be retrieved  Perhaps objcopy reveals further information    EDIT  The tool s name is of course nm  The flag -g is used to show only exported symbols

[c++] How do I list the symbols in a .so file

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