autoconf: System Services

1 
1 5.11 System Services
1 ====================
1 
1 The following macros check for operating system services or
1 capabilities.
1 
1  -- Macro: AC_PATH_X
1      Try to locate the X Window System include files and libraries.  If
1      the user gave the command line options `--x-includes=DIR' and
1      `--x-libraries=DIR', use those directories.
1 
1      If either or both were not given, get the missing values by running
1      `xmkmf' (or an executable pointed to by the `XMKMF' environment
1      variable) on a trivial `Imakefile' and examining the makefile that
1      it produces.  Setting `XMKMF' to `false' disables this method.
1 
1      If this method fails to find the X Window System, `configure'
1      looks for the files in several directories where they often reside.
1      If either method is successful, set the shell variables
1      `x_includes' and `x_libraries' to their locations, unless they are
1      in directories the compiler searches by default.
1 
1      If both methods fail, or the user gave the command line option
1      `--without-x', set the shell variable `no_x' to `yes'; otherwise
1      set it to the empty string.
1 
1  -- Macro: AC_PATH_XTRA
1      An enhanced version of `AC_PATH_X'.  It adds the C compiler flags
1      that X needs to output variable `X_CFLAGS', and the X linker flags
1      to `X_LIBS'.  Define `X_DISPLAY_MISSING' if X is not available.
1 
1      This macro also checks for special libraries that some systems
1      need in order to compile X programs.  It adds any that the system
1      needs to output variable `X_EXTRA_LIBS'.  And it checks for
1      special X11R6 libraries that need to be linked with before
1      `-lX11', and adds any found to the output variable `X_PRE_LIBS'.
1 
1 
1  -- Macro: AC_SYS_INTERPRETER
1      Check whether the system supports starting scripts with a line of
1      the form `#!/bin/sh' to select the interpreter to use for the
1      script.  After running this macro, shell code in `configure.ac'
1      can check the shell variable `interpval'; it is set to `yes' if
1      the system supports `#!', `no' if not.
1 
1  -- Macro: AC_SYS_LARGEFILE
1      Arrange for 64-bit file offsets, known as large-file support
1      (http://www.unix-systems.org/version2/whatsnew/lfs20mar.html).  On
1      some hosts, one must use special compiler options to build
1      programs that can access large files.  Append any such options to
1      the output variable `CC'.  Define `_FILE_OFFSET_BITS' and
1      `_LARGE_FILES' if necessary.
1 
1      Large-file support can be disabled by configuring with the
1      `--disable-largefile' option.
1 
1      If you use this macro, check that your program works even when
1      `off_t' is wider than `long int', since this is common when
1      large-file support is enabled.  For example, it is not correct to
1      print an arbitrary `off_t' value `X' with `printf ("%ld", (long
1      int) X)'.
1 
1      The LFS introduced the `fseeko' and `ftello' functions to replace
1      their C counterparts `fseek' and `ftell' that do not use `off_t'.
1      Take care to use `AC_FUNC_FSEEKO' to make their prototypes
1      available when using them and large-file support is enabled.
1 
1  -- Macro: AC_SYS_LONG_FILE_NAMES
1      If the system supports file names longer than 14 characters, define
1      `HAVE_LONG_FILE_NAMES'.
1 
1  -- Macro: AC_SYS_POSIX_TERMIOS
1      Check to see if the Posix termios headers and functions are
1      available on the system.  If so, set the shell variable
1      `ac_cv_sys_posix_termios' to `yes'.  If not, set the variable to
1      `no'.
1