ldd output

Hello,

$ldd /usr/lib/libdl.so.1

give nothing in output/ Is this library ok ?

*ldd <other_lib.so>
libz.so.1 =>     /<custom_path>/libz.so.1
libz.so.1 (SUNW_1.1) => not found

with this error message, are the shared libraries (/<custom_path>/libz.so.1) always be badly compiled ?

tx you

You can define LD_LIBRARY_PATH to have a usual path structure to poin to directories.
You can also use crle

crle                                # list current ld config
crle -l  <custom_path>  -u  # will update the ld config.

Read the crle manpage first, it is easy to hose the ld config file.