Command Line to see the contents Shared Object Module(lib*.so)

Question

What is the command line to see the contents of a Shared Object module (lib*.so)?

Like how we use:

ar -t lib*.a

for archives(lib*.a) and it displays all the object files in the library.

EDIT1

Example

ar -t lib*.a

gives me a display:

asset.o

sldep.o

Lowborn

Answer 1

use nm -D --defined-only libname.so to get the symbol names from your dynamic library.
The --defined-only switch shows you only the symbol that are defined in these files, and not references to external functions.

An alternative is to use objdump, and catch only the symbols in the text section :

objdump -T /usr/lib/libjpeg.so | grep text
...
0001b5c0 g    DF .text  00000016  Base        jdiv_round_up
00003730 g    DF .text  00000417  Base        jpeg_set_colorspace
0000cda0 g    DF .text  000002de  Base        jpeg_consume_input
00002b30 g    DF .text  00000023  Base        jpeg_abort_compress
00003b50 g    DF .text  000000b6  Base        jpeg_default_colorspace
00002810 g    DF .text  00000067  Base        jpeg_suppress_tables
00004110 g    DF .text  00000130  Base        jpeg_add_quant_table
000100c0 g    DF .text  0000011f  Base        jpeg_save_markers
...

Baste

@Jack Kelly: The objdump util seems more comprehensive, but what's the difference wrt to the OP? – Nealneala

@Matt Joiner: The difference between this answer and mine is the reference to nm -D --defined-only. nm -D will display undefined symbols and so on, which is just noise if you want to see what the lib itself defines. – Interlard

How do you see the contents of each function? – Glarus

Answer 2

I think nm -D is what you're looking for.

$ nm -D /usr/lib/libpng.so
...
00000000000058f0 T png_reset_zstream
000000000000d420 T png_save_int_32
000000000000d450 T png_save_uint_16
000000000000d3f0 T png_save_uint_32
0000000000007810 T png_set_IHDR
0000000000007500 T png_set_PLTE
000000000000ce20 T png_set_add_alpha
0000000000006670 T png_set_asm_flags
0000000000006970 T png_set_bKGD
000000000001a740 T png_set_background
...

Interlard

I have created a dynamic library(lib*.so file) and added a few functions in it.so i need a command line that would display its contents.(i.e the functions) – Lowborn

How do you see the contents of each function? – Glarus

Answer 3

The nm -D command lists the dynamic symbols of your shared library, which seems to be exactly what you want.

Beasley