When you're developing a complex application, it may become difficult to understand how the runtime linker lays out the internal link maps and scopes of resolution. To help determine what exactly the runtime linker is doing, you can use the DL_DEBUG environment variable to make the linker display diagnostic messages.
Diagnostic messages are categorized, and the value of DL_DEBUG determines which categories are displayed. The special category help doesn't produce diagnostics messages, but rather displays a help message and then terminates the application.
To redirect diagnostic messages to a file, set the LD_DEBUG_OUTPUT environment variable to the full path of the output file.