44. Linux Shell Command, LDD

1. Description

DD-print shared library Dependencies

LDD [Option]... file...

2. Option

-U print unused direct dependencies. (Since glibc 2.3.4 .)

-D perform relocations and report any missing objects (ELF only ).

-R perform relocations for both data objects and functions, and report any missing objects or functions (ELF only ).

3. Others

1) LDD can display the dependency of the executable module by setting a series of environmental variables, such as ld_trace_loaded_objects and ld_library_version. [1] When the ld_trace_loaded_objects environment variable is not empty, any executableProgramDuring running, only the dependency of the module is displayed, and the program is not actually executed.

Export ld_trace_loaded_objects = 1

2) LDD shows how the dependency of the executable module works.Essentially through the ld-linux.so (the loader of the elf dynamic library). We know that,The LD-linux. So module will work before the executable module program and gain controlSo when those environment variables above are set, the ld-linux.so selects the dependency that shows the executable module.

3) LDD is not an executable program, but a shell script.

4) view the script in/usr/bin/LDD.

Reference

[1] introduce the implementation principle of LDD

Http://hi.baidu.com/jackywdx/blog/item/5b64d2518ed6d31f377abe33.html