LD(1) LD(1)
NAME
ld - loader
SYNOPSIS
ld [ option ] file ...
DESCRIPTION
Ld combines several object programs into one, resolves
external references, and searches libraries. In the sim-
plest case several object files are given, and ld combines
them, producing an object module which can be either exe-
cuted or become the input for a further ld run. (In the
latter case, the -r option must be given to preserve the
relocation bits.) The output of ld is left on a.out. This
file is made executable only if no errors occurred during
the load.
The argument routines are concatenated in the order speci-
fied. The entry point of the output is the beginning of the
first routine.
If any argument is a library, it is searched exactly once at
the point it is encountered in the argument list. Only
those routines defining an unresolved external reference are
loaded. If a routine from a library references another rou-
tine in the library, and the library has not been processed
by ranlib(1), the referenced routine must appear after the
referencing routine in the library. Thus the order of pro-
grams within libraries may be important. If the first mem-
ber of a library is named `__.SYMDEF', then it is understood
to be a dictionary for the library such as produced by
ranlib; the dictionary is searched iteratively to satisfy as
many references as possible.
The symbols `_etext', `_edata' and `_end' (`etext', `edata'
and `end' in C) are reserved, and if referred to, are set to
the first location above the program, the first location
above initialized data, and the first location above all
data respectively. It is erroneous to define these symbols.
Ld understands several options. Except for -l, they should
appear before the file names.
-s `Strip' the output, that is, remove the symbol table
and relocation bits to save space (but impair the use-
fulness of the debugger). This information can also be
removed by strip(1).
-u Take the following argument as a symbol and enter it as
undefined in the symbol table. This is useful for
LD(1) LD(1)
loading wholly from a library, since initially the sym-
bol table is empty and an unresolved reference is
needed to force the loading of the first routine.
-lx This option is an abbreviation for the library name
`/lib/libx.a', where x is a string. If that does not
exist, ld tries `/usr/lib/libx.a'. A library is
searched when its name is encountered, so the placement
of a -l is significant.
-x Do not preserve local (non-.globl) symbols in the out-
put symbol table; only enter external symbols. This
option saves some space in the output file.
-X Save local symbols except for those whose names begin
with `L'. This option is used by cc(1) to discard
internally generated labels while retaining symbols
local to routines.
-r Generate relocation bits in the output file so that it
can be the subject of another ld run. This flag also
prevents final definitions from being given to common
symbols, and suppresses the `undefined symbol' diagnos-
tics.
-d Force definition of common storage even if the -r flag
is present.
-n Arrange that when the output file is executed, the text
portion will be read-only and shared among all users
executing the file. This involves moving the data
areas up to the first possible 4K word boundary follow-
ing the end of the text.
-i When the output file is executed, the program text and
data areas will live in separate address spaces. The
only difference between this option and -n is that here
the data starts at location 0.
-o The name argument after -o is used as the name of the
ld output file, instead of a.out.
-e The following argument is taken to be the name of the
entry point of the loaded program; location 0 is the
default.
-O This is an overlay file, only the text segment will be
replaced by exec(2). Shared data must have the same
layout as in the program overlaid.
-D The next argument is a decimal number that sets the
size of the data segment.
LD(1) LD(1)
FILES
/lib/lib*.a libraries
/usr/lib/lib*.a more libraries
a.out output file
SEE ALSO
as(1), ar(1), cc(1), ranlib(1)
BUGS