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 [ -sacLT ] [ - ] [ -arch_only arch_type ] 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 imple-
mentor 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 shar-
ing 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 uni-
versal 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.
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 used.
For a dynamic shared library, this specifies the compatibility version number of the library. When a library is used the compati-
bility 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, -headerpad, -headerpad_max_install_names, -weak_ref-
erence_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 executed.
-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 cpusubtype.
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.
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.
One other option applies to both libtool and ranlib:
- Treat all remaining arguments as names of files (or archives) and not as options.
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. September 24, 2008 LIBTOOL(1)