How do I view the list of functions a Linux shared library is exporting?

Question

I want to view the exported functions of a shared library on Linux.

What command allows me to do this?

(On Windows I use the program depends)

a similar question: [How do i find out what all symbols are exported from a shared object?](http://stackoverflow.com/questions/1237575/how-do-i-find-out-what-all-symbols-are-exported-from-a-shared-object) — Ilia K., Jan 31 '13 at 22:14

score 377 · Accepted Answer · answered Dec 22 '10 at 23:50

377

What you need is nm and its -D option:

$ nm -D /usr/lib/libopenal.so.1
.
.
.
00012ea0 T alcSetThreadContext
000140f0 T alcSuspendContext
         U atanf
         U calloc
.
.
.

Exported sumbols are indicated by a T. Required symbols that must be loaded from other shared objects have a U. Note that the symbol table does not include just functions, but exported variables as well.

See the nm manual page for more information.

answered Dec 22 '10 at 23:50

thkala

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Or if you only want to see exported symbols, add the "--defined-only" flag. eg: "nm -D --defined-only /lib/libtest.so" – Shervin Emami May 20 '13 at 18:10
4

On Mac OS X just use `nm` without the `-D` flag. – JPaget Oct 21 '14 at 22:05
nm -D libmy.so | grep " T " – Aftershock Feb 06 '22 at 18:32
And add -C if C++ name-demangling is desired – Post Self May 25 '22 at 18:35

score 63 · Answer 2 · edited Apr 10 '14 at 20:42

63

objdump -T *.so may also do the job

edited Apr 10 '14 at 20:42

Jeroen Vannevel

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answered Apr 10 '14 at 20:01

user2391685

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score 8 · Answer 3 · edited Jun 02 '16 at 09:04

8

On a MAC, you need to use nm *.o | c++filt, as there is no -C option in nm.

edited Jun 02 '16 at 09:04

frogatto

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answered Jul 03 '15 at 15:30

Vincent Fenet

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score 6 · Answer 4 · answered Feb 20 '20 at 16:05

Among other already mentioned tools you can use also readelf (manual). It is similar to objdump but goes more into detail. See this for the difference explanation.

$ readelf -sW /lib/liblzma.so.5 |head -n10

Symbol table '.dynsym' contains 128 entries:
   Num:    Value  Size Type    Bind   Vis      Ndx Name
     0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 00000000     0 FUNC    GLOBAL DEFAULT  UND pthread_mutex_unlock@GLIBC_2.0 (4)
     2: 00000000     0 FUNC    GLOBAL DEFAULT  UND pthread_mutex_destroy@GLIBC_2.0 (4)
     3: 00000000     0 NOTYPE  WEAK   DEFAULT  UND _ITM_deregisterTMCloneTable
     4: 00000000     0 FUNC    GLOBAL DEFAULT  UND memmove@GLIBC_2.0 (5)
     5: 00000000     0 FUNC    GLOBAL DEFAULT  UND free@GLIBC_2.0 (5)
     6: 00000000     0 FUNC    GLOBAL DEFAULT  UND memcpy@GLIBC_2.0 (5)

How am I supposed to find exported symbols by using readelf? It gives me an overwhelming amount of output. — Juraj Martinka, Apr 02 '20 at 07:06
@JurajMartinka `readelf -sW *.so > out.txt` this will write the output into the file. — ibndias, Oct 12 '20 at 02:37

score 0 · Answer 5 · answered May 02 '21 at 17:46

0

Just in case some Mac user is looking here, use llvm-cxxdump or llvm-readelf -sW

answered May 02 '21 at 17:46

user941581

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How do I view the list of functions a Linux shared library is exporting?

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