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libtool - create libraries
ranlib - add or update the table of contents of archive
libraries
SYNOPSIS
libtool -static -o output [ -sacLT ] [ - ] [ -arch_only
arch_type ] file... [-filelist listfile[,dirname]]
libtool -dynamic -o output [ -install_name name ] [ -com-
patibility_version number ] [ -current_version number ] [
link editor flags ] [ -v ] [ -noall_load ] [ - ] [
-arch_only arch_type ] file... [-filelist list-
file[,dirname]]
ranlib [ -sact ] [ - ] archive...
DESCRIPTION
The libtool command takes the specified input object files
and creates a library for use with the link editor, ld(1).
The library's name is specified by output (the argument to
the -o flag). The input object files may be in any cor-
rect format that contains object files (``fat'' files,
archives, object files). Libtool will not put any non-
object input file into the output library (unlike ranlib,
which allows this in the archives it operates on).
When producing a ``fat'' file from objects of the same CPU
type and differing CPU subtypes, libtool and ranlib create
at most one library for each CPU type, rather than a sepa-
rate library in a fat file for each of the unique pairings
of CPU type and CPU subtype. Thus, the resulting CPU sub-
type for each library is the _ALL CPU subtype for that CPU
type. This strategy strongly encourages the implementor
of a library to create one library that chooses optimum
code to run at run time, rather than at link time.
Libtool can create either dynamically linked shared
libraries, with -dynamic, or statically linked (archive)
libraries, with -static.
DYNAMICALLY LINKED SHARED LIBRARIES
Dynamically linked libraries, unlike statically linked
libraries, are Mach-O format files and not ar(5) format
files. Dynamically linked libraries have two restric-
tions: No symbol may be defined in more than one object
file and no common symbol can be used. To maximize shar-
ing of a dynamically linked shared library the objects
should be compiled with the -dynamic flag of cc(1) to pro-
duce indirect undefined references and position-indepen-
dent code. To build a dynamically linked library,
libtool, runs the link editor, ld(1), with -dylib once for
each architecutre present in the input objects and then
Libtool with -static is intended to replace ar(5) and ran-
lib. For backward compatibility, ranlib is still avail-
able, and it supports fat files. Ranlib adds or updates
the table of contents to each archive so it can be linked
by the link editor, ld(1). The table of contents is an
archive member at the beginning of the archive that indi-
cates which symbols are defined in which library members.
Because ranlib rewrites the archive, sufficient temporary
file space must be available in the file system that con-
tains the current directory. Ranlib takes all correct
forms of libraries (fat files containing archives, and
simple archives) and updates the table of contents for all
archives in the file. Ranlib also takes one common incor-
rect form of archive, an archive whose members are fat
object files, adding or updating the table of contents and
producing the library in correct form (a fat file contain-
ing multiple archives).
The archive member name for a table of contents begins
with ``__.SYMDEF''. Currently, there are two types of
table of contents produced by libtool -static and ranlib
and understood by the link editor, ld(1). These are
explained below, under the -s and -a options.
OPTIONS
The following options pertain to libtool only.
-static
Produce a statically linked (archive) library from
the input files. This is the default.
-dynamic
Produce a dynamically linked shared library from
the input files.
-install_name name
ror a dynamic shared library this specifies the
file name the library will be installed in for pro-
grams that use it. If this is not specified the
name specified by the -o output option will be
used.
-compatibility_version number
For a dynamic shared library this specifies the
compatibility version number of the library. When
a library is used the compatibility version is
checked and if the user's version is greater that
the library's version, an error message is printed
and the using program exits. The format of number
is X[.Y[.Z]] where X must be a positive non-zero
number less than or equal to 65535, and .Y and .Z
are optional and if present must be positive non-
checking is done when the library is used.
-current_version number
For dynamic shared library files this specifies the
current version number of the library. The program
using the library can obtain the current version of
the library programmatically to determine exactly
which version of the library it is using. The for-
mat of number is X[.Y[.Z]] where X must be a posi-
tive non-zero number less than or equal to 65535,
and .Y and .Z are optional and if present must be
positive non-zero numbers less than or equal to
255. If this is not specified then it has a value
of 0.
-noall_load
For dynamic shared library files this specifies the
the default behavior of loading all members of
archives on the command line is not to be done.
This option is used by the GNU compiler driver,
cc(1), when used with it's -dynamiclib option.
This is done to allow selective loading of the
GNU's compiler's runtime support library,
libcc_dyanmic.a .
link editor flags
For a dynamic shared library the following ld(1)
flags are accepted and passed through: -lx, -Ldir,
-ysym, -initsym, -idefinition:indirect, -seg1addr,
-segs_read_only_addr, -segs_read_write_addr,
-seg_addr_table, -segprot, -segalign, -sectcreate,
-sectorder, -sectorder_detail, -sectalign, -unde-
fined, -read_only_relocs, -prebind, -noprebind,
-framework, -umbrella, -allowable_client,
-sub_umbrella, -F, -U, -Y, -Sn, -Si, -S, -X, -why-
load, -all_load. -arch_errors_fatal, -dylib_file,
-run_init_lazily, -final_output. See the ld(1) man
page for details on these flags. The flag
-image_base is a synonym for -seg1addr.
-v Verbose mode, which prints the ld(1) commands and
lipo(1) commands executed.
-filelist listfile[,dirname]
The listfile contains a list of file names and is
an alternative way of specifiying file names on the
command line. The file names are listed one per
line separated only by newlines (spaces and tabs
are assumed to be part of the file name). If the
optional directory name, dirname is specified then
it is prepended to each name in the list file.
This option causes libtool to build a library only
for the specified arch_type and ignores all other
architectures in the input files.
The following options pertain to the table of contents for
an archive library, and apply to both libtool -static and
ranlib:
-s Produce the preferred type of table of contents,
which results in faster link editing when linking
with the archive. The order of the table of con-
tents is sorted by symbol name. The library member
name of this type of table of contents is
``__.SYMDEF SORTED''. This type of table of con-
tents can only be produced when the library does
not have multiple members that define the same sym-
bol. This is the default.
-a Produce the original type of table of contents,
whose order is based on the order of the members in
the archive. The library member name of this type
of table of contents is ``__.SYMDEF''. This type
of table of contents must be used when the library
has multiple members that define the same symbol.
-c Include common symbols as definitions with respect
to the table of contents. This is seldom the
intended behavior for linking from a library, as it
forces the linking of a library member just because
it uses an uninitialized global that is undefined
at that point in the linking. This option is
included only because this was the original behav-
ior of ranlib. This option is not the default.
-L Use the 4.4bsd archive extended format #1, which
allows archive member names to be longer than 16
characters and have spaces in their names. This
option is the default.
-T Truncate archive member names to 16 characters and
don't use the 4.4bsd extended format #1. This
option is not the default.
For compatibility, the following ranlib option is accepted
(but ignored):
-t This option used to request that ranlib only
``touch'' the archives instead of modifying them.
The option is now ignored, and the table of con-
tents is rebuilt.
One other option applies to both libtool and ranlib:
archives) and not as options.
SEE ALSO
ld(1), ar(1), otool(1), make(1), redo_prebinding(1), ar(5)
BUGS
The way libraries use to be created, errors were possible
if the library was modified with ar(1) and the table of
contents was not updated by rerunning ranlib(1). Thus the
link editor, ld, warns when the modification date of a
library is more recent than the creation date of its table
of contents. Unfortunately, this means that you get the
warning even if you only copy the library.
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