LD(1) UNIX Reference Manual LD(1)
S
\bSY
\bYN
\bNO
\bOP
\bPS
\bSI
\bIS
\bS
l
\bld
\bd [option] ... _
\bf_
\bi_
\bl_
\be ...
D
\bDE
\bES
\bSC
\bCR
\bRI
\bIP
\bPT
\bTI
\bIO
\bON
\bN
L
\bLd
\bd combines several object programs into one, resolves external refer-
ences, and searches libraries. In the simplest case several object _
\bf_
\bi_
\bl_
\be_
\bs
are given, and l
\bld
\bd combines them, producing an object module which can be
either executed or become the input for a further l
\bld
\bd run. (In the latter
case, the -
\b-r
\br option must be given to preserve the relocation bits.) The
output of l
\bld
\bd is left on _
\ba._
\bo_
\bu_
\bt. This file is made executable only if no
errors occurred during the load.
The argument routines are concatenated in the order specified. The entry
point of the output is the beginning of the first routine (unless the -
\b-e
\be
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 un-
resolved external reference are loaded. If a routine from a library
references another routine in the library, and the library has not been
processed by ranlib(1), the referenced routine must appear after the re-
ferencing routine in the library. Thus the order of programs within li-
braries may be important. The first member of a library should be a file
named `__.SYMDEF', which is understood to be a dictionary for the library
as produced by ranlib(1); 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 lo-
cation above all data respectively. It is erroneous to define these sym-
L
\bLd
\bd understands several options. Except for -
\b-l
\bl, they should appear before
-
\b-A
\bA This option specifies incremental loading, i.e. linking is to be
done in a manner so that the resulting object may be read into an
already executing program. The next argument is the name of a file
whose symbol table will be taken as a basis on which to define ad-
ditional symbols. Only newly linked material will be entered into
the text and data portions of a.out, but the new symbol table will
reflect every symbol defined before and after the incremental load.
This argument must appear before any other object file in the argu-
ment list. The -
\b-T
\bT option may be used as well, and will be taken to
mean that the newly linked segment will commence at the correspond-
ing address (which must be a multiple of 1024). The default value
is the old value of _end.
-
\b-D
\bD Take the next argument as a hexadecimal number and pad the data
segment with zero bytes to the indicated length.
-
\b-d
\bd Force definition of common storage even if the -
\b-r
\br flag is present.
-
\b-e
\be The following argument is taken to be the name of the entry point
of the loaded program; location 0 is the default.
Add _
\bd_
\bi_
\br to the list of directories in which libraries are searched
for. Directories specified with -
\b-L
\bL are searched before the stan-
-
\b-l
\bl_
\bx This option is an abbreviation for the library name `_
\bl_
\bi_
\bb_
\bx._
\ba,' where
_
\bx is a string. L
\bLd
\bd searches for libraries first in any directories
specified with -
\b-L
\bL options, then in the standard directories /_
\bl_
\bi_
\bb,
/_
\bu_
\bs_
\br/_
\bl_
\bi_
\bb, and /_
\bu_
\bs_
\br/_
\bl_
\bo_
\bc_
\ba_
\bl/_
\bl_
\bi_
\bb. A library is searched when its name
is encountered, so the placement of a -
\b-l
\bl is significant.
-
\b-M
\bM produce a primitive load map, listing the names of the files which
-
\b-N
\bN Do not make the text portion read only or sharable. (Use "magic
-
\b-n
\bn Arrange (by giving the output file a 0410 "magic number") 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 1024 byte boundary follow-
-
\b-o
\bo The _
\bn_
\ba_
\bm_
\be argument after -
\b-o
\bo is used as the name of the l
\bld
\bd output
file, instead of _
\ba._
\bo_
\bu_
\bt.
-
\b-r
\br Generate relocation bits in the output file so that it can be the
subject of another l
\bld
\bd run. This flag also prevents final defini-
tions from being given to common symbols, and suppresses the `unde-
fined symbol' diagnostics.
-
\b-S
\bS `Strip' the output by removing all symbols except locals and glo-
-
\b-s
\bs `Strip' the output, that is, remove the symbol table and relocation
bits to save space (but impair the usefulness of the debuggers).
This information can also be removed by strip(1).
-
\b-T
\bT The next argument is a hexadecimal number which sets the text seg-
ment origin. The default origin is 0.
-
\b-t
\bt ("trace") Print the name of each file as it is processed.
-
\b-u
\bu Take the following argument as a symbol and enter it as undefined
in the symbol table. This is useful for loading wholly from a li-
brary, since initially the symbol table is empty and an unresolved
reference is needed to force the loading of the first routine.
-
\b-X
\bX 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.
-
\b-x
\bx Do not preserve local (non-.globl) symbols in the output symbol
table; only enter external symbols. This option saves some space
Indicate each file in which _
\bs_
\by_
\bm appears, its type and whether the
file defines or references it. Many such options may be given to
trace many symbols. (It is usually necessary to begin _
\bs_
\by_
\bm with an
`_', as external C, FORTRAN and Pascal variables begin with under-
-
\b-z
\bz Arrange for the process to be loaded on demand from the resulting
executable file (413 format) rather than preloaded. This is the
default. Results in a 1024 byte header on the output file followed
by a text and data segment each of which have size a multiple of
1024 bytes (being padded out with nulls in the file if necessary).
With this format the first few BSS segment symbols may actually ap-
pear (from the output of size(1)) to live in the data segment; this
to avoid wasting the space resulting from data segment size round-
/_
\bu_
\bs_
\br/_
\bl_
\bi_
\bb/_
\bl_
\bi_
\bb*._
\ba libraries
/_
\bu_
\bs_
\br/_
\bl_
\bo_
\bc_
\ba_
\bl/_
\bl_
\bi_
\bb/_
\bl_
\bi_
\bb*._
\ba more libraries
_
\ba._
\bo_
\bu_
\bt output file
S
\bSE
\bEE
\bE A
\bAL
\bLS
\bSO
\bO
as(1), ar(1), cc(1), ranlib(1)
H
\bHI
\bIS
\bST
\bTO
\bOR
\bRY
\bY
L
\bLd
\bd appeared in Version 6 AT&T Unix.
There is no way to force data to be page aligned. L
\bLd
\bd pads images which
are to be demand loaded from the file system to the next page boundary to
avoid a bug in the system.
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