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有人能提供一下ld命令的使用方法及详细参数吗？
$man ld
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User Commands ld(1)
NAME
ld - link-editor for object files
SYNOPSIS
/usr/ccs/bin/ld [ -64 ] [ -a | -r ] [ -b ] [ -c name ] [
-C ] [ -G ] [ -i ] [ -m ] [ -s ] [ -t ] [ -V ] [ -B
direct ] [ -B dynamic | static ] [ -B group ] [ -B
local ] [ -B eliminate ] [ -B reduce ] [ -B symbolic ] [
-d y | n ] [ -D token ] [ -e epsym ] [ -F name |
-f name ] [ -h name ] [ -I name ] [ -L path ] [ -l x ]
[ -M mapfile ] [ -N string ] [ -o outfile ] [ -p auditlib
] [ -P auditlib ] [ -Q y | n ] [ -R path ] [
-S supportlib ] [ -u symname ] [ -Y P,dirlist ] [ -z
absexec ] [ -z allextract | defaultextract | weakextract
] [ -z combreloc ] [ -z defs | nodefs ] [ -z endfiltee
] [ -z finiarray=function ] [ -z groupperm | nogroupperm
] [ -z ignore | record ] [ -z initarray=function ] [ -z
initfirst ] [ -z interpose ] [ -z lazyload | nolazyload
] [ -z loadfltr ] [ -z muldefs ] [ -z nodelete ] [ -z
nodefaultlib ] [ -z nodlopen ] [ -z nodump ] [ -z nopar-
tial ] [ -z noversion ] [ -z now ] [ -z origin ] [ -z
preinitarray=function ] [ -z redlocsym ] [ -z text |
textwarn | textoff ] filename ...
DESCRIPTION
The ld command combines relocatable object files, performs
relocation, and resolves external symbols. ld operates in
two modes, static or dynamic, as governed by the -d option.
In static mode, -dn, relocatable object files given as argu-
ments are combined to produce an executable object file. If
the -r option is specified, relocatable object files are
combined to produce one relocatable object file. In dynamic
mode, -dy, the default, relocatable object files given as
arguments are combined to produce an executable object file
that will be linked at execution with any shared object
files given as arguments. If the -G option is specified,
relocatable object files are combined to produce a shared
object. In all cases, the output of ld is left in a.out by
default.
If any argument is a library, ld searches exactly once at
the point it encounters the library in the argument list.
The library may be either a relocatable archive or a shared
object. For an archive library, ld loads only those rou-
tines that define an unresolved external reference. ld
searches the archive library symbol table sequentially with
as many passes as are necessary to resolve external refer-
ences that can be satisfied by library members. See
ar(3HEAD). Thus, the order of members in the library is
functionally unimportant, unless multiple library members
exist that define the same external symbol.
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User Commands ld(1)
A shared object consists of an indivisible, whole unit, that
has been generated by a previous link-edit of one or more
input files. When the link-editor processes a shared object,
the entire contents of the shared object become a logical
part of the resulting output file image. The shared object
is not physically copied during the link-edit as its actual
inclusion is deferred until process execution. This logical
inclusion means that all symbol entries defined in the
shared object are made available to the link-editing pro-
cess.
No command-line option is required to distinguish 32-bit or
64-bit objects. The link-editor uses the ELF class of the
first input relocatable file it sees to govern the mode in
which it will operate. Intermixing 32-bit and 64-bit objects
is not permitted. See also the -64 option.
OPTIONS
The following options are supported:
-64 Creates a 64-bit object. By default, the class of the
object being generated is determined from the first
ELF object processed from the command line. This
option is useful when creating an object directly with
ld whose input is solely from a mapfile (see the -M
option) or an archive library.
-a In static mode only, produces an executable object
file; gives errors for undefined references. This is
the default behavior for static mode. -a may not be
used with the -r option.
-b In dynamic mode only, does no special processing for
relocations that reference symbols in shared objects.
Without the -b option, the link-editor creates special
position-independent relocations for references to
functions defined in shared objects and arranges for
data objects defined in shared objects to be copied
into the memory image of an executable by the runtime
linker.
The -b option is intended for specialized dynamic
objects and is not recommended for general use. Its
use suppresses all specialized processing required to
insure an object's shareability, and may even prevent
the relocation of 64-bit executables.
-B direct
Establishes direct binding information by recording
the relationship between each symbol reference and the
dependency that provides the definition. The runtime
linker uses this information to search directly for
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User Commands ld(1)
the symbol in the associated object rather than to
carry out its default symbol search. Direct binding
information can only be established to dependencies
specified with the link-edit. Thus, you should use the
-z defs option. Objects that wish to interpose on sym-
bols in a direct binding environment should identify
themselves as interposers with the -z interpose
option. The use of -B direct enables -z lazyload for
all dependencies.
-B dynamic | static
Options governing library inclusion. -B dynamic is
valid in dynamic mode only. These options may be
specified any number of times on the command line as
toggles: if the -B static option is given, no shared
objects will be accepted until -B dynamic is seen. See
also the -l option.
-B eliminate
Causes any global symbols not assigned to a version
definition to be eliminated from the symbol table.
This option achieves the same symbol elimination as
the auto-elimination directive available as part of a
mapfile version definition.
-B group
Establishes a shared object and its dependencies as a
group. Objects within the group will be bound to other
members of the group at runtime. The runtime process-
ing of an object containing this flag mimics that
which occurs if the object is added to a process using
dlopen(3DL) with the RTLD_GROUP mode. An object that
has an explicit dependency on a object identified as a
group, will itself become a member of the group.
As the group must be self contained, use of the -B
group option also asserts the -z defs option.
-B local
Causes any global symbols, not assigned to a version
definition, to be reduced to local. Version defini-
tions can be supplied via a mapfile and indicate the
global symbols that should remain visible in the gen-
erated object. This option achieves the same symbol
reduction as the auto-reduction directive available as
part of a mapfile version definition and may be useful
when combining versioned and non-versioned relocatable
objects.
-B reduce
When generating a relocatable object, causes the
reduction of symbolic information defined by any
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User Commands ld(1)
version definitions. Version definitions can be sup-
plied via a mapfile to indicate the global symbols
that should remain visible in the generated object.
When a relocatable object is generated, by default
version definitions are only recorded in the output
image. The actual reduction of symbolic information
will be carried out when the object itself is used in
the construction of a dynamic executable or shared
object. This option is applied automatically when
dynamic executable or shared object is created.
-B symbolic
In dynamic mode only. When building a shared object,
binds references to global symbols to their defini-
tions, if available, within the object. Normally,
references to global symbols within shared objects are
not bound until runtime, even if definitions are
available, so that definitions of the same symbol in
an executable or other shared object can override the
object's own definition. ld will issue warnings for
undefined symbols unless -z defs overrides.
The -B symbolic option is intended for specialized
dynamic objects and is not recommended for general
use. To reduce the runtime relocation overhead of an
object, the creation of a version definition is recom-
mended.
-c name
Records the configuration file name for use at run-
time. Configuration files may be employed to alter
default search paths, provide a directory cache and
provide alternative object dependencies. See crle(1).
-C Demangles C++ symbol names displayed in diagnostic
messages.
-d y | n
When -d y, the default, is specified, ld uses dynamic
linking; when -d n is specified, ld uses static link-
ing. See also -B dynamic|static.
-D token,token,..
Prints debugging information, as specified by each
token, to the standard error. The special token help
indicates the full list of tokens available.
-e epsym
Sets the entry point address for the output file to be
that of the symbol epsym.
-f name
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User Commands ld(1)
Useful only when building a shared object. Specifies
that the symbol table of the shared object is used as
an auxiliary filter on the symbol table of the shared
object specified by name. Multiple instances of this
option are allowed. This option may not be combined
with the -F option.
-F name
Useful only when building a shared object. Specifies
that the symbol table of the shared object is used as
a filter on the symbol table of the shared object
specified by name. Multiple instances of this option
are allowed. This option may not be combined with the
-f option.
-G In dynamic mode only, produces a shared object. Unde-
fined symbols are allowed.
-h name
In dynamic mode only, when building a shared object,
records name in the object's dynamic section. name
will be recorded in executables that are linked with
this object rather than the object's UNIX System file
name. Accordingly, name will be used by the runtime
linker as the name of the shared object to search for
at runtime.
-i Ignores LD_LIBRARY_PATH. This option is useful when an
LD_LIBRARY_PATH setting is in effect to influence the
runtime library search, which would interfere with the
link-editing being performed.
-I name
When building an executable, uses name as the path
name of the interpreter to be written into the program
header. The default in static mode is no interpreter;
in dynamic mode, the default is the name of the run-
time linker, ld.so.1(1). Either case may be overridden
by -I name. exec(2) will load this interpreter when it
loads a.out and will pass control to the interpreter
rather than to a.out directly.
-l x Searches a library libx.so or libx.a, the conventional
names for shared object and archive libraries, respec-
tively. In dynamic mode, unless the -B static option
is in effect, ld searches each directory specified in
the library search path for a libx.so or libx.a file.
The directory search stops at the first directory con-
taining either. ld chooses the file ending in .so if
-lx expands to two files with names of the form
libx.so and libx.a. If no libx.so is found, then ld
accepts libx.a. In static mode, or when the -B static
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User Commands ld(1)
option is in effect, ld selects only the file ending
in .a. ld searches a library when it encounters its
name, so the placement of -l is significant.
-L path
Adds path to the library search directories. ld
searches for libraries first in any directories speci-
fied by the -L options and then in the standard direc-
tories. This option is useful only if it precedes the
-l options to which it applies on the command line.
The environment variable LD_LIBRARY_PATH may be used
to supplement the library search path (see
LD_LIBRARY_PATH below).
-m Produces a memory map or listing of the input/output
sections, together with any non-fatal multiply-defined
symbols, on the standard output.
-M mapfile
Reads mapfile as a text file of directives to ld. This
option may be specified multiple times. If mapfile is
a directory, then all regular files, as defined by
stat(2), within the directory will be processed. See
Linker and Libraries Guide for a description of map-
files. There are mapfiles in /usr/lib/ld that show
the default layout of programs as well as mapfiles for
linking 64-bit programs above or below 4 gigabytes.
See the FILES section below.
-N string
This option causes a DT_NEEDED entry to be added to
the .dynamic section of the object being built. The
value of the DT_NEEDED string will be the string
specified on the command line. This option is position
dependent, and the DT_NEEDED .dynamic entry will be
relative to the other dynamic dependencies discovered
on the link-edit line.
-o outfile
Produces an output object file named outfile. The name
of the default object file is a.out.
-p auditlib
Identifies an audit library, auditlib, that is used to
audit this object at runtime. Any shared object iden-
tified as requiring auditing of itself has this
requirement inherited by any object specifying this
shared object as a dependency (see -P option).
-P auditlib
Identifies an audit library, auditlib, that is used to
audit this object's dependencies at runtime.
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User Commands ld(1)
Dependency auditing can also be inherited from depen-
dencies identified as requiring auditing (see -p
option).
-Q y | n
Under -Q y, an ident string is added to the .comment
section of the output file to identify the version of
the link-editor used to create the file. This results
in multiple ld idents when there have been multiple
linking steps, such as when using ld -r. This is
identical with the default action of the cc command.
-Q n suppresses version identification.
-r Combines relocatable object files to produce one relo-
catable object file. ld will not complain about
unresolved references. This option cannot be used in
dynamic mode or with -a.
-R path
A colon-separated list of directories used to specify
library search directories to the runtime linker. If
present and not NULL, it is recorded in the output
object file and passed to the runtime linker. Multiple
instances of this option are concatenated together
with each path separated by a colon.
-s Strips symbolic information from the output file. Any
debugging information, that is .debug, .line, and
.stab sections, and their associated relocation
entries will be removed. Except for relocatable files
or shared objects, the symbol table and string table
sections will also be removed from the output object
file.
-S supportlib
The shared object supportlib is loaded with the link-
editor and given information regarding the linking
process. Support shared objects may also be supplied
using the SGS_SUPPORT environment variable. See Linker
and Libraries Guide for more details.
-t Turns off the warning for multiply-defined symbols
that have different sizes or alignments.
-u symname
Enters symname as an undefined symbol in the symbol
table. This is useful for loading entirely from an
archive library, since initially the symbol table is
empty, and an unresolved reference is needed to force
the loading of the first routine. The placement of
this option on the command line is significant; it
must be placed before the library that will define the
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User Commands ld(1)
symbol.
-V Outputs a message giving information about the version
of ld being used.
-Y P,dirlist
Changes the default directories used for finding
libraries. dirlist is a colon-separated path list.
-z absexec
Useful only when building a dynamic executable. Speci-
fies that references to external absolute symbols
should be resolved immediately instead of being left
for resolution at runtime. In very specialized cir-
cumstances, this option removes text relocations that
can result in excessive swap space demands by an exe-
cutable.
-z allextract | defaultextract | weakextract
Alters the extraction criteria of objects from any
archives that follow. By default, archive members are
extracted to satisfy undefined references and to pro-
mote tentative definitions with data definitions. Weak
symbol references do not trigger extraction. Under -z
allextract, all archive members are extracted from the
archive. Under -z weakextract, weak references trigger
archive extraction. -z defaultextract provides a means
of returning to the default following use of the
former extract options.
-z combreloc
Combines multiple relocation sections. Reduces over-
head when objects are loaded into memory.
-z defs
Forces a fatal error if any undefined symbols remain
at the end of the link. This is the default when an
executable is built. It is also useful when building a
shared object to assure that the object is self-
contained, that is, that all its symbolic references
are resolved internally.
-z endfiltee
Marks a filtee so that when processed by a filter it
terminates any further filtee searches by the filter.
-z finiarray=function
Appends an entry to the .finiarray section of the
object being built. If no .finiarray section is
present, one is created. The new entry is initialized
to point to function. See Linker and Libraries Guide
for more details.
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User Commands ld(1)
-z groupperm | nogroupperm
Assigns, or deassigns each dependency that follows to
a unique group. Assigning a dependency to a group has
the same effect as if the dependency had been built
using the -B group option.
-z ignore | record
Ignores, or records, dynamic dependencies that are not
referenced as part of the link-edit. By default, -z
record is in effect.
-z initarray=function
Appends an entry to the .initarray section of the
object being built. If no .initarray section is
present, one is created. The new entry is initialized
to point to function. See Linker and Libraries Guide
for more details.
-z initfirst
Marks the object so that its runtime initialization
occurs before the runtime initialization of any other
objects brought into the process at the same time. In
addition, the object runtime finalization will occur
after the runtime finalization of any other objects
removed from the process at the same time. This option
is only meaningful when building a shared object.
-z interpose
Marks the object as an interposer. When direct bind-
ings are in effect (see -B direct), the runtime linker
will search for symbols in any interposers before the
object associated to the direct binding.
-z lazyload | nolazyload
Enables or disables the marking of dynamic dependen-
cies to be lazily loaded. Dynamic dependencies which
are marked lazyload will not be loaded at initial pro-
cess start-up, but instead will be delayed until the
first binding to the object is made.
-z loadfltr
Marks the object to require that when building a
filter, its filtees be processed immediately at run-
time. Normally, filter processing is delayed until a
symbol reference is bound to the filter. The runtime
processing of an object that contains this flag mimics
that which occurs if the LD_LOADFLTR environment vari-
able is in effect. See ld.so.1(1).
-z muldefs
Allows multiple symbol definitions. By default, multi-
ple symbol definitions that occur between relocatable
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User Commands ld(1)
objects will result in a fatal error condition. This
option suppresses the error condition and allows the
first symbol definition to be taken.
-z nodefs
Allows undefined symbols. This is the default when a
shared object is built. When used with executables,
the behavior of references to such undefined symbols
is unspecified.
-z nodelete
Marks the object as non-deletable at runtime. The run-
time processing of an object that contains this flag
mimics that which occurs if the object is added to a
process using dlopen(3DL) with the RTLD_NODELETE mode.
-z nodefaultlib
Marks the object so that the runtime default library
search path (used after any LD_LIBRARY_PATH or run-
paths) is ignored. This option implies that all depen-
dencies of the object can be satisfied from its run-
path.
-z nodlopen
Marks the object as not available to dlopen(3DL),
either as the object specified by the dlopen(), or as
any form of dependency required by the object speci-
fied by the dlopen(). This option is only meaningful
when building a shared object.
-z nodump
Marks the object as not available to dldump(3DL).
-z nopartial
If there are any partially initialized symbols in the
input relocatable object files, the partially initial-
ized symbols are expanded when the output file is gen-
erated.
-z noversion
Does not record any versioning sections. Any version
sections or associated .dynamic section entries will
not be generated in the output image.
-z now
Marks the object to override the runtime linker's
default mode and require non-lazy runtime binding.
This is similar to adding the object to the process by
using dlopen(3DL) with the RTLD_NOW mode, or setting
the LD_BIND_NOW environment variable in effect. See
ld.so.1(1).
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User Commands ld(1)
-z origin
Marks the object as requiring immediate $ORIGIN pro-
cessing at runtime.
-z preinitarray=function
Appends an entry to the .preinitarray section of the
object being built. If no .preinitarray section is
present, one is created. The new entry is initialized
to point to function. See Linker and Libraries Guide
for more details.
-z redlocsym
Eliminates all local symbols except for the SECT sym-
bols from the symbol table SHT_SYMTAB. All relocations
that refer to local symbols will be updated to refer
to the corresponding SECT symbol.
-z text
In dynamic mode only, forces a fatal error if any
relocations against non-writable, allocatable sections
remain.
-z textoff
In dynamic mode only, allows relocations against all
allocatable sections, including non-writable ones.
This is the default when building a shared object.
-z textwarn
In dynamic mode only, lists a warning if any reloca-
tions against non-writable, allocatable sections
remain. This is the default when building an execut-
able.
ENVIRONMENT VARIABLES
LD_LIBRARY_PATH
A list of directories in which to search for libraries
specified with the -l option. Multiple directories are
separated by a colon. In the most general case, it
will contain two directory lists separated by a semi-
colon:
dirlist1;dirlist2
If ld is called with any number of occurrences of -L,
as in:
ld ... -Lpath1 ... -Lpathn ...
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User Commands ld(1)
then the search path ordering is:
dirlist1 path1 ... pathn dirlist2 LIBPATH
When the list of directories does not contain a semi-
colon, it is interpreted as dirlist2.
The LD_LIBRARY_PATH environment variable also affects
the runtime linkers searching for dynamic dependen-
cies.
This environment variable can be specified with a _32
or _64 suffix. This makes the environment variable
specific, respectively, to 32-bit or 64-bit processes
and overrides any non-suffixed version of the environ-
ment variable that may be in effect.
LD_OPTIONS
A default set of options to ld. LD_OPTIONS is inter-
preted by ld just as though its value had been placed
on the command line, immediately following the name
used to invoke ld, as in:
ld $LD_OPTIONS ... other-arguments ...
LD_RUN_PATH
An alternative mechanism for specifying a runpath to
the link-editor (see -R option). If both LD_RUN_PATH
and the -R option are specified, -R supersedes.
SGS_SUPPORT
Provides a colon-separated list of shared objects that
are loaded with the link-editor and given information
regarding the linking process. See also the -S
option.
Notice that environment variable-names beginning with the
characters 'LD_' are reserved for possible future enhance-
ments to ld and ld.so.1(1).
FILES
libx.so
libraries
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User Commands ld(1)
libx.a
libraries
a.out output file
LIBPATH
usually /usr/lib or /usr/lib/64 for 64-bit libraries.
/usr/lib/ld/map.default
mapfile showing default layout of 32-bit programs
/usr/lib/ld/sparcv9/map.default
mapfile showing default layout of 64-bit SPARCV9 pro-
grams
/usr/lib/ld/sparcv9/map.above4G
mapfile showing suggested layout above 4 gigabytes of
64-bit SPARCV9 programs
/usr/lib/ld/sparcv9/map.below4G
mapfile showing suggested layout below 4 gigabytes of
64-bit SPARCV9 programs
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWtoo |
|_____________________________|_____________________________|
SEE ALSO
as(1), crle(1), gprof(1), ld.so.1(1), pvs(1), exec(2),
stat(2), dlopen(3DL), dldump(3DL), elf(3ELF), a.out(4),
ar(3HEAD), attributes(5)
Linker and Libraries Guide Binary Compatibility Guide
SunOS 5.8 Last change: 10 Jan 2001 13
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