.TH ld.so 8 "30 October 2000"
.SH NAME
ld.so, ld-linux.so* \- dynamic linker/loader
.SH DESCRIPTION
.B ld.so
loads the shared libraries needed by a program, prepares the program
to run, and then runs it.
Unless explicitly specified via the
.B \-static
option to
.B ld
during compilation, all Linux programs are incomplete and require 
further linking at run time.
.PP
The necessary shared libraries needed by the program are searched for 
in the following order
.IP o
Using the DT_RPATH dynamic section attribute of the binary if present and
DT_RUNPATH attribute does not exist.
.IP o
Using the environment variable
.B LD_LIBRARY_PATH .
Except if the executable is a setuid/setgid binary, in which case it
is ignored.
.IP o
Using the DT_RUNPATH dynamic section attribute of the binary if present.
.IP o
From the cache file
.BR /etc/ld.so.cache
which contains a compiled list of candidate libraries previously found
in the augmented library path. If, however, the binary was linked with
.B -z nodeflib
linker option, libraries in the default library paths are skipped.
.IP o
In the default path
.BR /lib ,
and then
.BR /usr/lib .
If the binary was linked with
.B -z nodeflib
linker option, this step is skipped.
.SH SYNOPSIS
The dynamic linker can be run either indirectly through running some
dynamically linked program or library (in which case no command line options
to the dynamic linker can be passed and the dynamic linker which is stored
in the
.B .interp
section of the program is executed) or directly by running:
.P
.B /lib/ld-linux.so.*
[OPTIONS] [PROGRAM [ARGUMENTS]]
.SH COMMAND LINE OPTIONS
.TP
.B --list
List all dependencies and how they are resolved.
.TP
.B --verify
Verify that program is dynamically linked and this dynamic linker can handle
it.
.TP
.B --library-path PATH
Override
.B LD_LIBRARY_PATH
environment variable setting (see below).
.TP
.B --ignore-rpath LIST
Ignore RPATH and RUNPATH information in object names in LIST.
.SH ENVIRONMENT
.TP
.B LD_LIBRARY_PATH
A colon-separated list of directories in which to search for
ELF libraries at execution-time.
Similar to the 
.B PATH
environment variable.
.TP
.B 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 setuid will be loaded.
.TP
.B LD_TRACE_LOADED_OBJECTS
If set to non-empty string, causes the program to list its dynamic library
dependencies, as if run by ldd, instead of running normally.
.TP
.B LD_BIND_NOW
If set to non-empty string, causes the dynamic linker to resolve all symbols
at program startup instead of deferring function call resolval to the point
when they are first referenced.
.TP
.B LD_WARN
If set to non-empty string, warn about unresolved symbols.
.TP
.B LD_DEBUG
Output verbose debugging information about the dynamic linker.
If set to
.B all
prints all debugging information it has, if set to
.B help
prints a help message about which categories can be specified in this
environment variable.
.TP
.B LD_DEBUG_OUTPUT
File where
.B LD_DEBUG
output should be fed into, default is standard output. LD_DEBUG_OUTPUT
is ignored for setuid/setgid binaries.
.TP
.B LD_VERBOSE
If set to non-empty string, output symbol versioning information about the
program if querying information about the program (ie. either
.B LD_TRACE_LOADED_OBJECTS
has been set, or
.B --list
or
.B --verify
options have been given to the dynamic linker).
.SH FILES
.PD 0
.B /lib/ld-linux.so.*
ELF dynamic linker/loader
.TP
.B /etc/ld.so.cache
File containing a compiled list of directories in which to search for
libraries and an ordered list of candidate libraries.
.TP
.B /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.
.TP
.B lib*.so*
shared libraries
.PD
.SH SEE ALSO
.BR ldd (1),
.BR ldconfig (8).
.SH AUTHORS
Roland McGrath, Ulrich Drepper and others.
This man page is derived from libc 5 ld.so manual page.