ld.so
NAME
ld.so/ld-linux.so - dynamic linker/loader
DESCRIPTION
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 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.
- 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
environment 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 ALSO
ldd(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
Torvalds, Lars Wirzenius and Mitch D'Souza (not necessarily in that order).