lk(1)lk(1)Namelk - link editor
Syntaxlk [option...] file...
Description
The command combines several object programs into one, resolves exter‐
nal references, and searches libraries. In the simplest case, several
object files are given, and combines them, producing an object module
which can be executed. The output of is always a standard ULTRIX
object module. This file is made executable only if no errors occurred
during the load.
The argument routines are linked together in the order specified. The
entry point of the output is the beginning of the first routine, unless
the -e option is specified.
If the argument is a library, it is searched only 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 routine in the library and the library has not been
processed by the referenced routine must appear after the referencing
routine in the library. Thus the order of programs within libraries
may be important. The first member of a library should be a file named
`__.SYMDEF', which is a dictionary for the library as produced by The
dictionary is searched repeatedly to satisfy as many references as pos‐
sible.
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 in that order. It is an error to define
these symbols.
Like the linker, the linker can process ULTRIX object modules, files,
archived libraries (.a files), and ranlib-generated indexed libraries.
Unlike the linker, however, the linker can also process object modules
generated by the VAX FORTRAN compiler. All command options can also be
specified on the command.
Options
The command has several options. Except for -l, they should appear
before the file names.
-D number Sets data segment length. The `number' is a number
specifying the desired length of the data segment.
The linker pads the data segment to this length
with zero bytes.
-e symbol Take the argument as the name of the entry point of
the loaded program. Location 0 is the default.
-H number Takes number argument as a decimal integer, adds it
to end of text, and starts data section at a higher
address.
-K Produces full load map, cross-referencing all
defined symbols.
-Ldir Add dir to the list of directories in which
libraries are searched for. Directories specified
with -L are searched before the standard directo‐
ries.
-lx Abbreviation for the library name `/lib/libx.a',
where x is a string. If that does not exist, tries
`/usr/lib/libx.a' A library is searched when its
name is encountered, so the placement of a -l is
significant.
-M Produces full load map, consisting of a module and
program section synopsis and symbol cross-refer‐
ence. Only symbols that are referenced appear in
the cross-reference. Use -K to cross-reference all
symbols.
-N Do not make text portion read only or sharable.
(Use magic number 0407.)
-n Arranges (by giving the output file a 0410 ``magic
number'') that when the output file is executed,
the text portion is read-only and shared among all
users executing the file. This involves moving the
data areas up to the first possible 1024 byte
boundary following the end of the text.
-o name Takes the name argument after -o as the name of the
output file, instead of
-S Strips the output by removing all symbols except
locals and globals.
-s Removes the symbol table and relocation bits to
save space. This impairs the usefulness of the
debuggers. This information can also be removed by
-T number Takes the argument as a hexadecimal number which
sets the text segment origin. The default origin
is 0.
-t Displays the name of each file as it is processed.
-u symbol Enters argument as undefined symbol in symbol ta‐
ble. This is useful for loading from a library,
since initially the symbol table is empty and an
unresolved reference is needed to force the loading
of the first routine.
-X Saves local symbols except for those whose names
begin with `L'. This option is used by to discard
internally-generated labels while retaining symbols
local to routines.
-x Suppresses saving nonglobal symbols in output sym‐
bol table; enters only external symbols. This
option saves some space in the output file.
-Yenvironment Adjust the magic number in the output file so that
the program runs in the specified environment .
The parameter can be POSIX, SYSTEM_FIVE, or BSD.
The parameter sets the program's execution environ‐
ment to conform with one of the three standards.
This parameter overrides the PROG_ENV environment
variable, if it is present. If neither this param‐
eter nor the PROG_ENV variable is present, -YBSD is
assumed.
-ysym Indicates each file in which sym appears, its type
and whether the file defines or references it.
Many such options may be given to trace many sym‐
bols. (It is usually necessary to begin sym with
an `_', as external C and PASCAL variables begin
with underscores.)
-z Loads process on demand from the resulting exe‐
cutable file (413 format) rather than preloaded.
This is the default. It results in a 1024 byte
header on the output file followed by a text and
data segment, whose size is 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 appear, from the out‐
put of to live in the data segment. This avoids
wasting the space which results from the data seg‐
ment size roundup.
The linker does not support the following options: -A, -d, or -r.
Restrictions
The command pads the images which are to be demand loaded from the file
system to the next page boundary.
When linking code containing GFLOAT instructions, the GFLOAT versions
of libc and/or the math library must be used rather than the normal
DFLOAT versions. Link to these by using -lcg and/or -lmg.
The compiler and the linker cannot detect the use of mixed double
floating point types, and your program may produce erroneous results.
Files
/lib/lib*.a libraries
/usr/lib/lib*.a libraries
/usr/local/lib/lib*.a libraries
a.out output file
a.map map file
See Alsoar(1), as(1), cc(1), ld(1), ranlib(1)
VAX lk(1)
