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37.2 Dynamic Linker Environment Variables ¶

The behavior of the dynamic linker can be modified through various environment variables.

LD_DEBUG ¶

The LD_DEBUG environment variable can be set to a comma-separated list of keywords to enable debugging output from the dynamic linker. Setting it to help will display a list of all available keywords. The output is written to standard output by default.

libs

Display library search paths.

reloc

Display relocation processing.

files

Display progress for input file processing.

symbols

Display symbol table processing.

bindings

Display information about symbol binding.

versions

Display version dependencies.

scopes

Display scope information.

tls

Display information about Thread-Local Storage (TLS) handling, including TCB allocation, deallocation, and reuse. This is useful for debugging issues related to thread creation and lifecycle.

all

All previous options combined.

statistics

Display relocation statistics.

unused

Determined unused DSOs.

help

Display a help message with all available options and exit.

LD_DEBUG_OUTPUT ¶

If LD_DEBUG is set, the output is written to standard output by default. If LD_DEBUG_OUTPUT is set, the output is written to the file specified by its value, with the process ID appended. For example, if LD_DEBUG_OUTPUT is set to /tmp/glibc.debug, the output will be written to a file named /tmp/glibc.debug.12345, where 12345 is the process ID.