ld.so(8)ld.so(8)NAME
ld.so/ld-linux.so - dynamic linker/loader
DESCRIPTION
ld.so loads the shared libraries needed by a program, prepares the pro‐
gram to run, and then runs it. Unless explicitly specified via the
-static option to ld during compilation, all Linux programs are incom‐
plete 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 exe‐
cutable 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
library path.
o In the default path /usr/lib, and then /lib.
ENVIRONMENT
LD_LIBRARY_PATH
A colon-separated list of directories in which to search for ELF
libraries at execution-time. Similar to the PATH environment
variable.
LD_PRELOAD
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
loaded.
LD_TRACE_LOADED_OBJECTS
If present, causes the program to list its dynamic library
dependencies, as if run by ldd, instead of running normally.
LD_BIND_NOW
If present, causes the dynamic linker to resolve all symbols at
program startup instead of when they are first referenced.
LD_AOUT_LIBRARY_PATH
A colon-separated list of directories in which to search for
a.out libraries at execution-time. Similar to the PATH environ‐
ment variable.
LD_AOUT_PRELOAD
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
Suppress warnings about a.out libraries with incompatible minor
version numbers.
LD_KEEPDIR
Don't ignore the directory in the names of a.out libraries to be
loaded. Use of this option is strongly discouraged.
FILES
/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
libraries.
lib*.so* shared libraries
SEE ALSOldd(1), ldconfig(8).
BUGS
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.
AUTHORS
David Engel, Eric Youngdale, Peter MacDonald, Hongjiu Lu, Linus Tor‐
valds, Lars Wirzenius and Mitch D'Souza (not necessarily in that
order).
14 March 1998 ld.so(8)
