using the nm tool to examine dynamic libraries, have discovered significant differences between macOS and Linux:
On Linux:
The -D flag must be specified to obtain the corresponding symbols.
Without -D, no symbols are displayed.
root@be00d9b1c2c9:/lib/aarch64-linux-gnu# nm -gU liblua5.4.so
nm: liblua5.4.so: no symbols
root@be00d9b1c2c9:/lib/aarch64-linux-gnu# nm -gDU liblua5.4.so
0000000000000000 A LUA_5.4
0000000000026a40 T luaL_addgsub@@LUA_5.4
00000000000269a0 T luaL_addlstring@@LUA_5.4
0000000000026a04 T luaL_addstring@@LUA_5.4
On macOS:
There's no -D flag. The nm command displays all symbols (including dynamic ones) by default.
❯ nm -gDU libcjson.dylib
/Library/Developer/CommandLineTools/usr/bin/nm: error: libcjson.dylib: File format has no dynamic symbol table
homebrew/lib on stable via v21.7.2
❯ nm -gU libcjson.dylib
0000000000002ab8 T cJSON_AddArrayToObject
0000000000002720 T cJSON_AddBoolToObject
0000000000002690 T cJSON_AddFalseToObject
0000000000002440 T cJSON_AddItemReferenceToArray
0000000000002520 T cJSON_AddItemReferenceToObject
homebrew/lib on stable via v21.7.2
The reason for this difference is that macOS and Linux use different formats for their executable files and handle symbol tables differently:
On Linux systems, the pkg-config --libs command does not output the -L path for dynamic libraries installed in the system's default search paths
For example:
root@be00d9b1c2c9:/usr/lib/aarch64-linux-gnu# pkg-config --libs lua5.4
-llua5.4
This output only includes the -l flag to specify the library name, but does not include the -L flag to specify the library path. This is because the library is located in the system's default search path.
will search valid path from below conf
/etc/ld.so.conf.d/*.conf/etc/ld.so.conf
nm tool
dynamic symbol
using the
nmtool to examine dynamic libraries, have discovered significant differences between macOS and Linux: On Linux:The
-Dflag must be specified to obtain the corresponding symbols.Without
-D, no symbols are displayed.On macOS:
There's no
-Dflag. Thenmcommand displays all symbols (including dynamic ones) by default.The reason for this difference is that macOS and Linux use different formats for their executable files and handle symbol tables differently:
Linux uses the ELF format.
macOS uses the Mach-O format.
[x] #829
symbol version
On Linux, symbols may appear with version declarations separated by @@ https://tldp.org/HOWTO/Program-Library-HOWTO/shared-libraries.html
dynamic lib search
pkg-config
On Linux systems, the pkg-config --libs command does not output the -L path for dynamic libraries installed in the system's default search paths
For example: root@be00d9b1c2c9:/usr/lib/aarch64-linux-gnu# pkg-config --libs lua5.4 -llua5.4
This output only includes the -l flag to specify the library name, but does not include the -L flag to specify the library path. This is because the library is located in the system's default search path.
will search valid path from below conf
/etc/ld.so.conf.d/*.conf/etc/ld.so.conf/etc/ld.so.conf.d/*.conf's fetch , need the os.ReadDirso & dylib
On Linux, dynamic library names end with .so
Related Bugs & Patch