Most Unix-like systems have a "search path" specifying file-system directories in which to look for dynamic libraries. Some systems specify the default path in a configuration file, others hard-code it into the dynamic loader. Some executable file formats can specify additional directories in which to search for libraries for a particular program. This can usually be overridden with an environment variable, although it is disabled for setuid and setgid programs, so that a user can't force such a program to run arbitrary code with root permissions. Developers of libraries are encouraged to place their dynamic libraries in places in the default search path. On the downside, this can make installation of new libraries problematic, and these "known" locations quickly become home to an increasing number of library files, making management more complex.