ld.so/ld-linux.so - dynamic linker/loader
ld.so loads the shared libraries needed by a program, prepares the program
to run, and then runs it. Unless explicitly specified via the
-static option to ld during compilation, all Linux programs are incomplete
and require further linking at run time.
The necessary shared libraries needed by the program are searched for
in the following order
o Using the environment variable LD_LIBRARY_PATH
(LD_AOUT_LIBRARY_PATH for a.out programs). Except if the executable
is a setuid/setgid binary, in which case it is ignored.
o From the cache file /etc/ld.so.cache which contains a compiled
list of candidate libraries previously found in the augmented
o In the default path /usr/lib, and then /lib.
A colon-separated list of directories in which to search for ELF
libraries at execution-time. Similar to the PATH environment
LD_PRELOAD [Toc] [Back]
A whitespace-separated list of additional, user-specified, ELF
shared libraries to be loaded before all others. This can be
used to selectively override functions in other shared
libraries. For setuid/setgid ELF binaries, only libraries in
the standard search directories that are also setgid will be
LD_TRACE_LOADED_OBJECTS [Toc] [Back]
If present, causes the program to list its dynamic library
dependencies, as if run by ldd, instead of running normally.
LD_BIND_NOW [Toc] [Back]
If present, causes the dynamic linker to resolve all symbols at
program startup instead of when they are first referenced.
LD_AOUT_LIBRARY_PATH [Toc] [Back]
A colon-separated list of directories in which to search for
a.out libraries at execution-time. Similar to the PATH environment
LD_AOUT_PRELOAD [Toc] [Back]
The name of an additional, user-specified, a.out shared library
to be loaded after all others. This can be used to selectively
override functions in other shared libraries.
LD_NOWARN [Toc] [Back]
Suppress warnings about a.out libraries with incompatible minor
LD_KEEPDIR [Toc] [Back]
Don't ignore the directory in the names of a.out libraries to be
loaded. Use of this option is strongly discouraged.
/lib/ld.so a.out dynamic linker/loader
/lib/ld-linux.so.* ELF dynamic linker/loader
/etc/ld.so.cache File containing a compiled list of directories in
which to search for libraries and an ordered list
of candidate libraries.
/etc/ld.so.preload File containing a whitespace separated list of ELF
shared libraries to be loaded before the program.
libraries and an ordered list of candidate
lib*.so* shared libraries
Currently ld.so has no means of unloading and searching for compatible
or newer version of libraries.
ld.so functionality is only available for executables compiled using
libc version 4.4.3 or greater.
David Engel, Eric Youngdale, Peter MacDonald, Hongjiu Lu, Linus Torvalds,
Lars Wirzenius and Mitch D'Souza (not necessarily in that
14 March 1998 ld.so(8)
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