ld(1)
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LD(1) NetBSD Reference Manual LD(1)
NAME
ld - link editor
SYNOPSIS
ld [-MNnrSstXxz] [-A symbol-file] [-assert keyword] [-Blinkmode]
[-D datasize] [-d c] [-d p] [-e entry] [-llibrary-specifier]
[-Llibrary-search-path] [-nostdlib] [-o filename] [-T address]
[-u symbol] [-V shlib-version] [-y symbol]
DESCRIPTION
ld combines the object and archive files given on the command line into a
new object file. The output object file is either an executable program,
a shared object suitable for loading at run-time, or an object file that
can once again be processed by ld. Object files and archives are pro-
cessed in the order given on the command line.
The options are as follows:
-A symbol-file
The symbol-file is taken as a base for link-editing the object
files on the command line.
-assert keyword
This option has currently no effect. It is here for compatibility
with SunOS ld. All conditions which would cause a Sun assertion
to fail will currently always cause error or warning messages
from ld.
-Bdynamic
Specifies that linking against dynamic libraries can take place.
If a library specifier of the form -lx appears on the command
line, ld searches for a library of the from libx.so.n.m (see the
-l option) according to the search rules in effect. If such a
file can not be found a traditional archive is looked for. This
options can appear anywhere on the command line and is complemen-
tary to -Bstatic.
-Bstatic
The counterpart of -Bdynamic. This option turns off dynamic
linking for all library specifiers until a -Bdynamic is once
again given. Any explicitly mentioned shared object encountered
on the command line while this option is in effect is flagged as
an error.
-Bshareable
Instructs the linker to build a shared object from the object
files rather than a normal executable image.
-Bsymbolic
Causes symbolic references to symbols within the object to be re-
solved and changed to base-relative references. This can be
used, e.g., to make a shared library use an internal symbol when
the executable that loads it has its own definition. References
to undefined symbols are not affected by this flag.
-Bforcearchive
Force all members of archives to be loaded, whether or not such
members contribute a definition to any plain object files. Useful
for making a shared library from an archive of PIC objects with-
out having to unpack the archive.
-Bsilly
Search for .sa silly archive companions of shared objects. Useful
for compatibility with version 3 shared objects.
-D data-size
Set the size of the data segment. For sanity's sake, this should
be larger than the cumulative data sizes of the input files.
-d c Force allocation of commons even producing relocatable output.
-d p Force alias definitions of procedure calls in non-PIC code. Use-
ful to obtain shareable code in the presence of run-time reloca-
tions as such calls will be re-directed through the Procedure
Linkage Table (see link(5))
-e entry-symbol
Specifies the entry symbol for an executable.
-Lpath Add path to the list of directories to search for libraries spec-
ified with the -l option.
-llib-spec
This option specifies a library to be considered for inclusion in
the output. If the -Bdynamic option is in effect, a shared li-
brary of the form lib<spec>.so.m.n (where m is the major, and n
is the minor version number, respectively) is searched for first.
The library with the highest version found in the search path is
selected. If no shared library is found or the -Bstatic option
is in effect, an archive of the form lib<spec>.a is looked for in
the library search path.
-M Produce output about the mapping of segments of the input files
and the values assigned to (global) symbols in the output file.
-N Produce a OMAGIC output file.
-n Produce a NMAGIC output file.
-nostdlib
Do not search the built-in path (usually ``/usr/lib'') for -l
specified libraries.
-o filename
Specifies the name of the output file. Defaults to ``a.out''.
-Q Produce a QMAGIC output file.
-r Produce relocatable object file, suitable for another pass
through ld.
-R Record the given path within the executable for run-time library
search. This only applies to dynamically linked executables.
-S Strip all debugger symbols from the output.
-s Strip all symbols from the output.
-T Specifies the start address of the text segment, with respect to
which all input files will be relocated.
-t Leave a trace of the input files as they are processed.
-u symbol
Force symbol to be marked as undefined. Useful to force loading
of an archive member in the absence of any other references to
that member.
-V version
Put the given version number into the output shared library (if
one is created). Useful to make shared libaries compatible with
other operating systems. Eg. SunOS 4.x libraries use version num-
ber 3. Defaults to 8.
-X Discard local symbols in the input files that start with the let-
ter ``L''
-x Discard all local symbols in the input files.
-y symbol
Trace the manipulations inflicted on symbol
-z Make a ZMAGIC output file. This is the default.
Transitional Compatibility
Use of the following directives is required on ELF systems and is recom-
mended on all others in order to prepare for the planned transition from
COFF to ELF.
-rpath dir
Record the given dir within the executable for run-time library
search, as for -R. Ignored on COFF systems.
-shared
Instructs the linker to build a shared object from the object
files rather than a normal executable image.
-soname library-name
The linker input file name is usually the plain ``.so'' file with
no version number. On ELF systems, this option sets the DT_SON-
AME field of a shared library to libraryname, which should be
specified with the major number and without the minor number. A
program image linked with this library will use at run time the
file name specified here rather than the linker input file name.
--whole-archive
A positional qualifier to force loading from archives. For each
archive mentioned on the commandline after this option, include
every object file from the archive in the link, rather than
searching the archive for the required object files. This is nor-
mally used when building shared libraries.
On COFF systems, the positional syntax is not currently imple-
mented; --whole-archive is treated exactly as -Bforcearchive.
--no-whole-archive
This option turns off the effect of a preceding --whole-archive
for any subsequent archive files on the command line. It is cur-
rently ignored on COFF systems.
--export-dynamic
Specifies that all symbols should be added to the dynamic symbol
table. This option is needed only by programs that make run-time
decisions to load modules they were never linked with. Ignored on
COFF systems.
ENVIRONMENT
ld utilizes the following environment variables:
LD_LIBRARY_PATH This colon-separated list of directories is inserted in-
to the search path for libraries following any directo-
ries specified via -L options and preceding the built-in
path.
LD_NOSTD_PATH When set, do not search the built-in path for libraries.
This is an alternative to the -nostdlib command-line
flag.
SEE ALSO
ld.so(1), link(5), ldconfig(8)
CAVEATS
An entry point must now explicitly be given if the output is intended to
be a normal executable program. This was not the case for the previous
version of ld.
BUGS
Shared objects are not properly checked for undefined symbols.
Cascading of shared object defeats the ``-Bstatic'' option.
All shared objects presented to ld are marked for run-time loading in the
output file, even if no symbols are needed from them.
HISTORY
The shared library model employed by ld appeared first in SunOS 4.0.
NetBSD 1.4 October 14, 1993 4
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