LIBTOOL(1) General Commands Manual LIBTOOL(1)
libtool - create libraries
ranlib - add or update the table of contents of archive libraries
libtool -static -o output [ -sacLTD ] [ - ] [ -arch_only arch_type ] [
-no_warning_for_no_symbols ] file... [-filelist listfile[,dirname]]
libtool -dynamic -o output [ -install_name name ] [
-compatibility_version number ] [ -current_version number ] [ link editor
flags ] [ -v ] [ -noall_load ] [ - ] [ -arch_only arch_type ] [ -V ]
file... [-filelist listfile[,dirname]]
ranlib [ -sactfqLT ] [ - ] archive...
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 correct format that contains object files
(``universal'' 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 ``universal'' 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 separate library in a universal file for
each of the unique pairings of CPU type and CPU subtype. Thus, the
resulting CPU subtype 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 restrictions: No symbol may be defined in more than
one object file and no common symbol can be used. To maximize sharing of
a dynamically linked shared library the objects should be compiled with
the -dynamic flag of cc(1) to produce indirect undefined references and
position-independent code. To build a dynamically linked library,
libtool, runs the link editor, ld(1), with -dylib once for each
architecture present in the input objects and then lipo(1) to create a
universal file if needed.
ARCHIVE (or statically linked) LIBRARIES
Libtool with -static is intended to replace ar(5) and ranlib. For
backward compatibility, ranlib is still available, and it supports
universal 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
indicates 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 contains the current directory. Ranlib
takes all correct forms of libraries (universal files containing
archives, and simple archives) and updates the table of contents for all
archives in the file. Ranlib also takes one common incorrect form of
archive, an archive whose members are universal object files, adding or
updating the table of contents and producing the library in correct form
(a universal file containing 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.
The following options pertain to libtool only.
@file Arguments beginning with @ are replaced by arguments read from the
specified file, as an alternative to listing those arguments on
the command line. The files simply contain libtool options and
files separated by whitespace: spaces, tabs, and newlines.
Characters can be escaped with a backslash (\), including
whitespace characters and other backslashes. Also, arguments that
include whitespace can be enclosed, wholly or in part, by single-
or double-quote charcters. These files may contain @file
references to additional files, although libtool will error on
include cycles. If a file cannot be found, the original @file
argument will remain in the argument list.
Produce a statically linked (archive) library from the input
files. This is the default.
Produce a dynamically linked shared library from the input files.
For a dynamic shared library, this specifies the file name the
library will be installed in for programs that use it. If this is
not specified the name specified by the -o output option will be
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 non-
negative numbers less than or equal to 255. If this is not
specified then it has a value of 0 and no checking is done when
the library is used.
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
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 non-negative numbers less than or equal to 255.
If this is not specified then it has a value of 0.
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_dynamic.a .
link editor flags
For a dynamic shared library the following ld(1) flags are
accepted and passed through: -lx, -weak-lx, -search_paths_first
-weak_library, -Ldir, -ysym, -usym, -initsym,
-idefinition:indirect, -seg1addr, -segs_read_only_addr,
-segs_read_write_addr, -seg_addr_table, -seg_addr_table_filename,
-segprot, -segalign, -sectcreate, -sectorder, -sectorder_detail,
-sectalign, -undefined, -read_only_relocs, -prebind,
-prebind_all_twolevel_modules, -prebind_allow_overlap, -noprebind,
-framework, -weak_framework, -umbrella, -allowable_client,
-sub_umbrella, -sub_library, -F, -U, -Y, -Sn, -Si, -Sp, -S, -X,
-x, -whyload, -all_load. -arch_errors_fatal, -dylib_file,
-run_init_lazily, -final_output, -macosx_version_min,
-multiply_defined, -multiply_defined_unused, -twolevel_namespace,
-twolevel_namespace_hints, -flat_namespace, -nomultidefs,
-weak_reference_mismatches, -M, -t, -no_arch_warnings,
-single_module, -multi_module, -exported_symbols_list,
-unexported_symbols_list, -m, -dead_strip,
-no_dead_strip_inits_and_terms, -executable_path, -syslibroot,
-no_uuid. 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
-V Print the version of libtool.
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. When building a dynamic library, if this is
specified with a specific cpusubtype other than the family
cpusubtype then libtool it does not use the ld(1)
-force_cpusubtype_ALL flag and passes the -arch_only argument to
ld(1) as the -arch flag so that the output is tagged with that
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 contents is sorted by symbol name. The library
member name of this type of table of contents is ``__.SYMDEF
SORTED''. This type of table of contents can only be produced
when the library does not have multiple members that define the
same symbol. 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 behavior 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.
-f Warns when the output archive is universal and ar(1) will no
longer be able to operate on it.
-q Do nothing if a universal file would be created.
-D When building a static library, set archive contents' user ids,
group ids, dates, and file modes to reasonable defaults. This
allows libraries created with identical input to be identical to
each other, regardless of time of day, user, group, umask, and
other aspects of the environment.
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 contents is rebuilt.
Other options applying to both libtool and ranlib:
- Treat all remaining arguments as names of files (or archives) and
not as options.
Don't warn about file that have no symbols.
Write an Xcode dependency info file describing a successful build
operation. This file describes the inputs directly or indirectly
used to create the library or dylib.
ld(1), ar(1), otool(1), make(1), redo_prebinding(1), ar(5)
With the way libraries used 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). So previously the link editor, ld(1), generated
an error when the modification date of a library was more recent than the
creation date of its table of contents. Unfortunately, this meant that
you got the error even if you only copy the library. Since this error
was found to be too much of a nuisance it was removed. So now it is
possible again to get link errors if the library is modified and the
table of contents is not updated.
Apple Inc. June 23, 2020 LIBTOOL(1)