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Exam objective 2.214.6 has a weight of 1, and verifies that candidates are able to identify, diagnose, and repair local system issues when using software from the command line. When you run a program, not everything you run comes directly out of the executable file. Some of the executable code is in the shared libraries. When the program starts running it's the responsibility of LD to make sure all the needed shared library modules are loaded into memory. LD.so is the run-time linker that finishes the link operation begun when the program was originally compiled. Any libraries that are not already loaded into memory are loaded at this point. The shared libraries may not be in the same locations they were when the program was compiled, so LD uses a file that lists their locations on the local machine. This file is constructed by a program called LDconfig. This program is run by any installation procedure that adds a new shared library to the system. You can run it, too, to fix any library references problems that you may have. It does more than just create the LD configuration file, it constructs symbolic links, which may be used to resolve the library names. You can change kernel configuration parameters at run time. The kernel parameters are available in the proc directory. To look at the values and change the values, you can use the syscontrol program. The A option lists all the values, and there are lots of them. You can name what you want to see by naming it on the command line. And you can change a value by using the W option, or you can change several values at once by putting the new value settings in the file Syscontrol.conf. You can use the P option on syscontrol to have the definitions in the file applied immediately, like that. You need to know the sorts of things you can read and set with syscontrol. You can look at the files and directory names with LS, and you can look at the values with CAT, but you could look at them more easily with syscontrol and you can set the values to explore the sys directory and see what's there. It's unlikely that you'll need to use LDconfig unless you do something unique. But you need to know how it works and what it does. Spend a little time with its MAN page.