转：借助LD_DEBUG环境变量调试共享库

LD_DEBUG is an environment variable for debugging library problem. The following example shows how to use it.
LD_DEBUG是一个用来调试共享库的环境变量，将其设置为help并运行任意程序即可看到他的使用说明

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利用 LD_DEBUG 这个环境变量可以清楚的看到解析过程
LD_DEBUG=help ls
Valid options for the LD_DEBUG environment variable are:? libs??????? display library search paths
? reloc?????? display relocation processing
? files?????? display progress for input file
? symbols???? display symbol table processing
? bindings??? display information about symbol binding
? versions??? display version dependencies
? all???????? all previous options combined
? statistics? display relocation statistics
? unused????? determined unused DSOs
? help??????? display this help message and exit?To direct the debugging output into a file instead of standard output
a filename can be specified using the LD_DEBUG_OUTPUT environment variable.

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