Copyright (c) 1991, 1992 Free Software Foundation
See section COPYING for conditions for redistribution
\(** .. ld - the GNU linker

ld "[\|" -o " output\c \|] \c objfile\c .\|.\|.

"[\|" -A\c architecture\c \|] "[\|" "-b "\c input-format\c \|] "[\|" -Bstatic "\|]" "[\|" "-c "\c commandfile\c \|] "[\|" -d | -dc | -dp\c \|]

"[\|" "-defsym "\c symbol\c = \c expression\c \|] "[\|" "-e "\c entry\c \|] "[\|" -F "\|]" "[\|" "-F "\c format\c \|] "[\|" "-format "\c input-format\c \|] "[\|" -g "\|]" "[\|" -G\c size\c \|] "[\|" --help "\|]" "[\|" -i "\|]" "[\|" -l\c ar\c \|] "[\|" -L\c searchdir\c \|] "[\|" -M "\|]" "[\|" -Map\c mapfile\c \|] "[\|" -m\c emulation\c \|] "[\|" -n | -N "\|]" "[\|" -noinhibit-exec "\|]" "[\|" "-oformat "\c output-format\c \|] "[\|" "-R "\c filename\c \|] "[\|" -relax "\|]" "[\|" -r | -Ur "\|]" "[\|" -S "\|]" "[\|" -s "\|]" "[\|" -sort-common "\|]" "[\|" "-T "\c commandfile\c \|] "[\|" "-Ttext "\c textorg\c \|] "[\|" "-Tdata "\c dataorg\c \|] "[\|" "-Tbss "\c bssorg\c \|] "[\|" -t "\|]" "[\|" "-u "\c sym\c ] "[\|" -V "\|]" "[\|" -v "\|]" "[\|" --version "\|]" "[\|" -warn-common "\|]" "[\|" -X "\|]" "[\|" -x "\|]"

\c ld\c combines a number of object and archive files, relocates their data and ties up symbol references. Often the last step in building a new compiled program to run is a call to \c ld\c . \c ld\c accepts Linker Command Language files to provide explicit and total control over the linking process. This man page does not describe the command language; see the `\|\c ld\c \|' entry in `\|\c info\c \|', or the manual ld: the GNU linker , for full details on the command language and on other aspects of the GNU linker. This version of \c ld\c uses the general purpose BFD libraries to operate on object files. This allows \c ld\c to read, combine, and write object files in many different formats\(emfor example, COFF or \c a.out\c . Different formats may be linked together to produce any available kind of object file. You can use `\|\c objdump -i\c \|' to get a list of formats supported on various architectures; see objdump ( 1 ). Aside from its flexibility, the GNU linker is more helpful than other linkers in providing diagnostic information. Many linkers abandon execution immediately upon encountering an error; whenever possible, \c ld\c continues executing, allowing you to identify other errors (or, in some cases, to get an output file in spite of the error). The GNU linker \c ld\c is meant to cover a broad range of situations, and to be as compatible as possible with other linkers. As a result, you have many choices to control its behavior through the command line, and through environment variables. The plethora of command-line options may seem intimidating, but in actual practice few of them are used in any particular context. For instance, a frequent use of \c ld\c is to link standard Unix object files on a standard, supported Unix system. On such a system, to link a file \c hello.o\c :

$ ld -o output /lib/crt0.o hello.o -lc

This tells \c ld\c to produce a file called \c output\c as the result of linking the file \c /lib/crt0.o\c with \c hello.o\c and the library \c libc.a\c which will come from the standard search directories. The command-line options to \c ld\c may be specified in any order, and may be repeated at will. For the most part, repeating an option with a different argument will either have no further effect, or override prior occurrences (those further to the left on the command line) of an option. The exceptions\(emwhich may meaningfully be used more than once\(emare \c -A\c , \c -b\c (or its synonym \c -format\c ), \c -defsym\c , \c -L\c , \c -l\c , \c -R\c , and \c -u\c . The list of object files to be linked together, shown as \c objfile\c , may follow, precede, or be mixed in with command-line options; save that an \c objfile\c argument may not be placed between an option flag and its argument. Usually the linker is invoked with at least one object file, but other forms of binary input files can also be specified with \c -l\c , \c -R\c , and the script command language. If \c no\c binary input files at all are specified, the linker does not produce any output, and issues the message `\|\c No input files\c \|'. Option arguments must either follow the option letter without intervening whitespace, or be given as separate arguments immediately following the option that requires them.

"-A" "architecture"\c \& In the current release of \c ld\c , this option is useful only for the Intel 960 family of architectures. In that \c ld\c configuration, the \c architecture\c argument is one of the two-letter names identifying members of the 960 family; the option specifies the desired output target, and warns of any incompatible instructions in the input files. It also modifies the linker's search strategy for archive libraries, to support the use of libraries specific to each particular architecture, by including in the search loop names suffixed with the string identifying the architecture. For example, if your \c ld\c command line included `\|\c -ACA\c \|' as well as `\|\c -ltry\c \|', the linker would look (in its built-in search paths, and in any paths you specify with \c -L\c ) for a library with the names

try

libtry.a

tryca

libtryca.a

The first two possibilities would be considered in any event; the last two are due to the use of `\|\c -ACA\c \|'. Future releases of \c ld\c may support similar functionality for other architecture families. You can meaningfully use \c -A\c more than once on a command line, if an architecture family allows combination of target architectures; each use will add another pair of name variants to search for when \c -l\c \& specifies a library.

"-b " "input-format"\c \& Specify the binary format for input object files that follow this option on the command line. You don't usually need to specify this, as \c ld\c is configured to expect as a default input format the most usual format on each machine. \c input-format\c is a text string, the name of a particular format supported by the BFD libraries. \c -format \c input-format\c \c has the same effect, as does the script command TARGET . You may want to use this option if you are linking files with an unusual binary format. You can also use \c -b\c to switch formats explicitly (when linking object files of different formats), by including \c -b \c input-format\c \c before each group of object files in a particular format. The default format is taken from the environment variable GNUTARGET\c . You can also define the input format from a script, using the command \c TARGET\c .

-Bstatic This flag is accepted for command-line compatibility with the SunOS linker, but has no effect on \c ld\c .

"-c " "commandfile"\c \& Directs \c ld\c to read link commands from the file \c commandfile\c . These commands will completely override \c ld\c 's default link format (rather than adding to it); \c commandfile\c must specify everything necessary to describe the target format. You may also include a script of link commands directly in the command line by bracketing it between `\|\c {\c \|' and `\|\c }\c \|' characters.

-d

-dc

-dp These three options are equivalent; multiple forms are supported for compatibility with other linkers. Use any of them to make \c ld\c \& assign space to common symbols even if a relocatable output file is specified (\c -r\c ). The script command \c FORCE_COMMON_ALLOCATION\c has the same effect.

"-defsym " "symbol"\c = \c expression\c \& Create a global symbol in the output file, containing the absolute address given by \c expression\c . You may use this option as many times as necessary to define multiple symbols in the command line. A limited form of arithmetic is supported for the \c expression\c in this context: you may give a hexadecimal constant or the name of an existing symbol, or use \c +\c and \c -\c to add or subtract hexadecimal constants or symbols. If you need more elaborate expressions, consider using the linker command language from a script.

"-e " "entry"\c Use \c entry\c as the explicit symbol for beginning execution of your program, rather than the default entry point. for a discussion of defaults and other ways of specifying the entry point.

-F

"-F" "format"\c \& Some older linkers used this option throughout a compilation toolchain for specifying object-file format for both input and output object files. \c ld\c 's mechanisms (the \c -b\c or \c -format\c options for input files, the \c TARGET\c command in linker scripts for output files, the \c GNUTARGET\c environment variable) are more flexible, but but it accepts (and ignores) the \c -F\c option flag for compatibility with scripts written to call the old linker.

"-format " "input-format"\c \& Synonym for \c -b\c \c input-format\c .

-g Accepted, but ignored; provided for compatibility with other tools.

"-G " "size"\c Set the maximum size of objects to be optimized using the GP register to size under MIPS ECOFF. Ignored for other object file formats.

--help Print a summary of the command-line options on the standard output and exit. This option and --version begin with two dashes instead of one for compatibility with other GNU programs. The other options start with only one dash for compatibility with other linkers.

-i Perform an incremental link (same as option \c -r\c ).

"-l" "ar"\c Add an archive file \c ar\c to the list of files to link. This option may be used any number of times. \c ld\c will search its path-list for occurrences of \c lib\c ar\c .a\c for every \c ar\c \& specified.

"-L" "searchdir"\c This command adds path \c searchdir\c to the list of paths that \c ld\c will search for archive libraries. You may use this option any number of times. The default set of paths searched (without being specified with \c -L\c ) depends on what emulation mode \c ld\c is using, and in some cases also on how it was configured. The paths can also be specified in a link script with the \c SEARCH_DIR\c \& command.

-M Print (to the standard output file) a link map\(emdiagnostic information about where symbols are mapped by \c ld\c , and information on global common storage allocation.

"-Map " "mapfile"\c Print to the file mapfile a link map\(emdiagnostic information about where symbols are mapped by \c ld\c , and information on global common storage allocation.

"-m " "emulation"\c Emulate the emulation linker. You can list the available emulations with the -V option. This option overrides the compiled-in default, which is the system for which you configured ld .

-N specifies readable and writable \c text\c and \c data\c sections. If the output format supports Unix style magic numbers, the output is marked as \c OMAGIC\c . When you use the `\|\c -N\c \|' option, the linker does not page-align the data segment.

-n sets the text segment to be read only, and \c NMAGIC\c is written if possible.

-noinhibit-exec Normally, the linker will not produce an output file if it encounters errors during the link process. With this flag, you can specify that you wish the output file retained even after non-fatal errors.

"-o " "output"\c \& output\c \& \c output\c is a name for the program produced by \c ld\c ; if this option is not specified, the name `\|\c a.out\c \|' is used by default. The script command \c OUTPUT\c can also specify the output file name.

"-oformat " "output-format"\c \& Specify the binary format for the output object file. You don't usually need to specify this, as \c ld\c is configured to produce as a default output format the most usual format on each machine. \c output-format\c is a text string, the name of a particular format supported by the BFD libraries. The script command OUTPUT_FORMAT can also specify the output format, but this option overrides it.

"-R " "filename"\c \& file\c \& Read symbol names and their addresses from \c filename\c , but do not relocate it or include it in the output. This allows your output file to refer symbolically to absolute locations of memory defined in other programs.

-relax An option with machine dependent effects. Currently this option is only supported on the H8/300. On some platforms, use this option to perform global optimizations that become possible when the linker resolves addressing in your program, such as relaxing address modes and synthesizing new instructions in the output object file. On platforms where this is not supported, `\|\c -relax\c \|' is accepted, but has no effect.

-r Generates relocatable output\(emi.e., generate an output file that can in turn serve as input to \c ld\c . This is often called \c partial linking\c . As a side effect, in environments that support standard Unix magic numbers, this option also sets the output file's magic number to \c OMAGIC\c . If this option is not specified, an absolute file is produced. When linking C++ programs, this option \c will not\c resolve references to constructors; \c -Ur\c is an alternative. This option does the same as \c -i\c .

-S Omits debugger symbol information (but not all symbols) from the output file.

-s Omits all symbol information from the output file.

-sort-common Normally, when ld places the global common symbols in the appropriate output sections, it sorts them by size. First come all the one byte symbols, then all the two bytes, then all the four bytes, and then everything else. This is to prevent gaps between symbols due to alignment constraints. This option disables that sorting.

"-Tbss " "org"\c

"-Tdata " "org"\c

"-Ttext " "org"\c Use \c org\c as the starting address for\(emrespectively\(emthe \c bss\c , \c data\c , or the \c text\c segment of the output file. \c textorg\c must be a hexadecimal integer.

"-T " "commandfile"\c \&

"-T" "commandfile"\c Equivalent to \c -c \c commandfile\c \c ; supported for compatibility with other tools.

-t Prints names of input files as \c ld\c processes them.

"-u " "sym" Forces \c sym\c to be entered in the output file as an undefined symbol. This may, for example, trigger linking of additional modules from standard libraries. \c -u\c may be repeated with different option arguments to enter additional undefined symbols.

-Ur For anything other than C++ programs, this option is equivalent to \c -r\c : it generates relocatable output\(emi.e., an output file that can in turn serve as input to \c ld\c . When linking C++ programs, \c -Ur\c \& \c will\c resolve references to constructors, unlike \c -r\c .

-V Display the version number for \c ld and list the supported emulations. Display which input files can and can not be opened.

-v Display the version number for \c ld\c .

--version Display the version number for \c ld and exit.

-warn-common Warn when a common symbol is combined with another common symbol or with a symbol definition. Unix linkers allow this somewhat sloppy practice, but linkers on some other operating systems do not. This option allows you to find potential problems from combining global symbols.

-X If \c -s\c or \c -S\c is also specified, delete only local symbols beginning with `\|\c L\c \|'.

-x If \c -s\c or \c -S\c is also specified, delete all local symbols, not just those beginning with `\|\c L\c \|'.

\c You can change the behavior of ld\c with the environment variable \c GNUTARGET\c . \c GNUTARGET\c determines the input-file object format if you don't use \c -b\c (or its synonym \c -format\c ). Its value should be one of the BFD names for an input format. If there is no \c GNUTARGET\c in the environment, \c ld\c uses the natural format of the host. If \c GNUTARGET\c is set to \c default\c then BFD attempts to discover the input format by examining binary input files; this method often succeeds, but there are potential ambiguities, since there is no method of ensuring that the magic number used to flag object-file formats is unique. However, the configuration procedure for BFD on each system places the conventional format for that system first in the search-list, so ambiguities are resolved in favor of convention.

objdump ( 1 )

"`\|" ld "\|' and `\|" binutils "\|'" entries in info\c

ld: the GNU linker\c , Steve Chamberlain and Roland Pesch; The GNU Binary Utilities\c , Roland H. Pesch.

Copyright (c) 1991, 1992 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.

Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be included in translations approved by the Free Software Foundation instead of in the original English.