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(libtool.info)libtool script contents
`libtool' script contents ========================= Since version 1.4, the `libtool' script is generated by `configure' (Note: Configuring). In earlier versions, `configure' achieved this by calling a helper script called `ltconfig'. From libtool version 0.7 to 1.0, this script simply set shell variables, then sourced the libtool backend, `ltmain.sh'. `ltconfig' from libtool version 1.1 through 1.3 inlined the contents of `ltmain.sh' into the generated `libtool', which improved performance on many systems. The tests that `ltconfig' used to perform are now kept in `libtool.m4' where thay can be written using Autoconf. This has the runtime performance benefits of inlined `ltmain.sh', _and_ improves the build time a little while considerably easing the amount of raw shell code that used to need maintaining. The convention used for naming variables which hold shell commands for delayed evaluation, is to use the suffix `_cmd' where a single line of valid shell script is needed, and the suffix `_cmds' where multiple lines of shell script *may* be delayed for later evaluation. By convention, `_cmds' variables delimit the evaluation units with the `~' character where necessary. Here is a listing of each of the configuration variables, and how they are used within `ltmain.sh' (Note: Configuring): - Variable: AR The name of the system library archiver. - Variable: CC The name of the C compiler used to configure libtool. - Variable: LD The name of the linker that libtool should use internally for reloadable linking and possibly shared libraries. - Variable: NM The name of a BSD-compatible `nm' program, which produces listings of global symbols in one the following formats: ADDRESS C GLOBAL-VARIABLE-NAME ADDRESS D GLOBAL-VARIABLE-NAME ADDRESS T GLOBAL-FUNCTION-NAME - Variable: RANLIB Set to the name of the ranlib program, if any. - Variable: allow_undefined_flag The flag that is used by `archive_cmds' in order to declare that there will be unresolved symbols in the resulting shared library. Empty, if no such flag is required. Set to `unsupported' if there is no way to generate a shared library with references to symbols that aren't defined in that library. - Variable: always_export_symbols Whether libtool should automatically generate a list of exported symbols using EXPORT_SYMBOLS_CMDS before linking an archive. Set to `yes' or `no'. Default is `no'. - Variable: archive_cmds - Variable: archive_expsym_cmds - Variable: old_archive_cmds Commands used to create shared libraries, shared libraries with `-export-symbols' and static libraries, respectively. - Variable: old_archive_from_new_cmds If the shared library depends on a static library, `old_archive_from_new_cmds' contains the commands used to create that static library. If this variable is not empty, `old_archive_cmds' is not used. - Variable: old_archive_from_expsyms_cmds If a static library must be created from the export symbol list in order to correctly link with a shared library, `old_archive_from_expsyms_cmds' contains the commands needed to create that static library. When these commands are executed, the variable SONAME contains the name of the shared library in question, and the $OBJDIR/$NEWLIB contains the path of the static library these commands should build. After executing these commands, libtool will proceed to link against $OBJDIR/$NEWLIB instead of SONAME. - Variable: build_libtool_libs Whether libtool should build shared libraries on this system. Set to `yes' or `no'. - Variable: build_old_libs Whether libtool should build static libraries on this system. Set to `yes' or `no'. - Variable: compiler_c_o Whether the compiler supports the `-c' and `-o' options simultaneously. Set to `yes' or `no'. - Variable: compiler_o_lo Whether the compiler supports compiling directly to a ".lo" file, i.e whether object files do not have to have the suffix ".o". Set to `yes' or `no'. - Variable: dlopen_support Whether `dlopen' is supported on the platform. Set to `yes' or `no'. - Variable: dlopen_self Whether it is possible to `dlopen' the executable itself. Set to `yes' or `no'. - Variable: dlopen_self_static Whether it is possible to `dlopen' the executable itself, when it is linked statically (`-all-static'). Set to `yes' or `no'. - Variable: echo An `echo' program which does not interpret backslashes as an escape character. - Variable: exclude_expsyms List of symbols that should not be listed in the preloaded symbols. - Variable: export_dynamic_flag_spec Compiler link flag that allows a dlopened shared library to reference symbols that are defined in the program. - Variable: export_symbols_cmds Commands to extract exported symbols from LIBOBJS to the file EXPORT_SYMBOLS. - Variable: extract_expsyms_cmds Commands to extract the exported symbols list from a shared library. These commands are executed if there is no file $OBJDIR/$SONAME-DEF, and should write the names of the exported symbols to that file, for the use of `old_archive_from_expsyms_cmds'. - Variable: fast_install Determines whether libtool will privilege the installer or the developer. The assumption is that installers will seldom run programs in the build tree, and the developer will seldom install. This is only meaningful on platforms in which SHLIBPATH_OVERRIDES_RUNPATH is not `yes', so FAST_INSTALL will be set to `needless' in this case. If FAST_INSTALL set to `yes', libtool will create programs that search for installed libraries, and, if a program is run in the build tree, a new copy will be linked on-demand to use the yet-to-be-installed libraries. If set to `no', libtool will create programs that use the yet-to-be-installed libraries, and will link a new copy of the program at install time. The default value is `yes' or `needless', depending on platform and configuration flags, and it can be turned from `yes' to `no' with the configure flag `--disable-fast-install'. - Variable: finish_cmds Commands to tell the dynamic linker how to find shared libraries in a specific directory. - Variable: finish_eval Same as FINISH_CMDS, except the commands are not displayed. - Variable: fix_srcfile_path Expression to fix the shell variable $srcfile for the compiler. - Variable: global_symbol_pipe A pipeline that takes the output of NM, and produces a listing of raw symbols followed by their C names. For example: $ eval "$NM progname | $global_symbol_pipe" D SYMBOL1 C-SYMBOL1 T SYMBOL2 C-SYMBOL2 C SYMBOL3 C-SYMBOL3 ... $ The first column contains the symbol type (used to tell data from code on some platforms), but its meaning is system dependent. - Variable: global_symbol_to_cdecl A pipeline that translates the output of GLOBAL_SYMBOL_PIPE into proper C declarations. On platforms whose linkers differentiate code from data, such as HP/UX, data symbols will be declared as such, and code symbols will be declared as functions. On platforms that don't care, everything is assumed to be data. - Variable: hardcode_action Either `immediate' or `relink', depending on whether shared library paths can be hardcoded into executables before they are installed, or if they need to be relinked. - Variable: hardcode_direct Set to `yes' or `no', depending on whether the linker hardcodes directories if a library is directly specified on the command line (such as `DIR/libNAME.a') when HARDCODE_LIBDIR_FLAG_SPEC is specified. - Variable: hardcode_into_libs Whether the platform supports hardcoding of run-paths into libraries. If enabled, linking of programs will be much simpler but libraries will need to be relinked during installation. Set to `yes' or `no'. - Variable: hardcode_libdir_flag_spec Flag to hardcode a LIBDIR variable into a binary, so that the dynamic linker searches LIBDIR for shared libraries at runtime. If it is empty, libtool will try to use some other hardcoding mechanism. - Variable: hardcode_libdir_separator If the compiler only accepts a single HARDCODE_LIBDIR_FLAG, then this variable contains the string that should separate multiple arguments to that flag. - Variable: hardcode_minus_L Set to `yes' or `no', depending on whether the linker hardcodes directories specified by `-L' flags into the resulting executable when HARDCODE_LIBDIR_FLAG_SPEC is specified. - Variable: hardcode_shlibpath_var Set to `yes' or `no', depending on whether the linker hardcodes directories by writing the contents of `$shlibpath_var' into the resulting executable when HARDCODE_LIBDIR_FLAG_SPEC is specified. Set to `unsupported' if directories specified by `$shlibpath_var' are searched at run time, but not at link time. - Variable: host - Variable: host_alias For information purposes, set to the specified and canonical names of the system that libtool was configured for. - Variable: include_expsyms List of symbols that must always be exported when using EXPORT_SYMBOLS. - Variable: libext The standard old archive suffix (normally "a"). - Variable: libname_spec The format of a library name prefix. On all Unix systems, static libraries are called `libNAME.a', but on some systems (such as OS/2 or MS-DOS), the library is just called `NAME.a'. - Variable: library_names_spec A list of shared library names. The first is the name of the file, the rest are symbolic links to the file. The name in the list is the file name that the linker finds when given `-lNAME'. - Variable: link_all_deplibs Whether libtool must link a program against all its dependency libraries. Set to `yes' or `no'. Default is `unknown', which is a synonym for `yes'. - Variable: link_static_flag Linker flag (passed through the C compiler) used to prevent dynamic linking. - Variable: need_lib_prefix Whether libtool should automatically prefix module names with 'lib'. Set to `yes' or `no'. By default, it is `unknown', which means the same as `yes', but documents that we are not really sure about it. `yes' means that it is possible both to `dlopen' and to link against a library without 'lib' prefix, i.e. it requires HARDCODE_DIRECT to be `yes'. - Variable: need_version Whether versioning is required for libraries, i.e. whether the dynamic linker requires a version suffix for all libraries. Set to `yes' or `no'. By default, it is `unknown', which means the same as `yes', but documents that we are not really sure about it. - Variable: need_locks Whether files must be locked to prevent conflicts when compiling simultaneously. Set to `yes' or `no'. - Variable: no_builtin_flag Compiler flag to disable builtin functions that conflict with declaring external global symbols as `char'. - Variable: no_undefined_flag The flag that is used by `archive_cmds' in order to declare that there will be no unresolved symbols in the resulting shared library. Empty, if no such flag is required. - Variable: objdir The name of the directory that contains temporary libtool files. - Variable: objext The standard object file suffix (normally "o"). - Variable: pic_flag Any additional compiler flags for building library object files. - Variable: postinstall_cmds - Variable: old_postinstall_cmds Commands run after installing a shared or static library, respectively. - Variable: postuninstall_cmds - Variable: old_postuninstall_cmds Commands run after uninstalling a shared or static library, respectively. - Variable: reload_cmds - Variable: reload_flag Commands to create a reloadable object. - Variable: runpath_var The environment variable that tells the linker which directories to hardcode in the resulting executable. - Variable: shlibpath_overrides_runpath Indicates whether it is possible to override the hard-coded library search path of a program with an environment variable. If this is set to no, libtool may have to create two copies of a program in the build tree, one to be installed and one to be run in the build tree only. When each of these copies is created depends on the value of `fast_install'. The default value is `unknown', which is equivalent to `no'. - Variable: shlibpath_var The environment variable that tells the dynamic linker where to find shared libraries. - Variable: soname_spec The name coded into shared libraries, if different from the real name of the file. - Variable: striplib - Variable: old_striplib Command to strip a shared (`striplib') or static (`old_striplib') library, respectively. If these variables are empty, the strip flag in the install mode will be ignored for libraries (Note: Install mode). - Variable: sys_lib_dlsearch_path_spec Expression to get the run-time system library search path. Directories that appear in this list are never hard-coded into executables. - Variable: sys_lib_search_path_spec Expression to get the compile-time system library search path. This variable is used by libtool when it has to test whether a certain library is shared or static. The directories listed in SHLIBPATH_VAR are automatically appended to this list, every time libtool runs (i.e., not at configuration time), because some linkers use this variable to extend the library search path. Linker switches such as `-L' also augment the search path. - Variable: thread_safe_flag_spec Linker flag (passed through the C compiler) used to generate thread-safe libraries. - Variable: version_type The library version numbering type. One of `libtool', `freebsd-aout', `freebsd-elf', `irix', `linux', `osf', `sunos', `windows', or `none'. - Variable: whole_archive_flag_spec Compiler flag to generate shared objects from convenience archives. - Variable: wl The C compiler flag that allows libtool to pass a flag directly to the linker. Used as: `${wl}SOME-FLAG'. Variables ending in `_cmds' or `_eval' contain a `~'-separated list of commands that are `eval'ed one after another. If any of the commands return a nonzero exit status, libtool generally exits with an error message. Variables ending in `_spec' are `eval'ed before being used by libtool.
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