The following macros check for operating system services or capabilities.
Try to locate the X Window System include files and libraries. If the user gave the command line options --x-includes=dir and --x-libraries=dir, use those directories.
If either or both were not given, get the missing values by running
xmkmf
(or an executable pointed to by theXMKMF
environment variable) on a trivial Imakefile and examining the makefile that it produces. SettingXMKMF
to ‘false’ disables this method.If this method fails to find the X Window System, configure looks for the files in several directories where they often reside. If either method is successful, set the shell variables
x_includes
andx_libraries
to their locations, unless they are in directories the compiler searches by default.If both methods fail, or the user gave the command line option --without-x, set the shell variable
no_x
to ‘yes’; otherwise set it to the empty string.
An enhanced version of
AC_PATH_X
. It adds the C compiler flags that X needs to output variableX_CFLAGS
, and the X linker flags toX_LIBS
. DefineX_DISPLAY_MISSING
if X is not available.This macro also checks for special libraries that some systems need in order to compile X programs. It adds any that the system needs to output variable
X_EXTRA_LIBS
. And it checks for special X11R6 libraries that need to be linked with before -lX11, and adds any found to the output variableX_PRE_LIBS
.
Check whether the system supports starting scripts with a line of the form ‘#!/bin/sh’ to select the interpreter to use for the script. After running this macro, shell code in configure.ac can check the shell variable
interpval
; it is set to ‘yes’ if the system supports ‘#!’, ‘no’ if not.
Arrange for 64-bit file offsets, known as large-file support. On some hosts, one must use special compiler options to build programs that can access large files. Append any such options to the output variable
CC
. Define_FILE_OFFSET_BITS
and_LARGE_FILES
if necessary.Large-file support can be disabled by configuring with the --disable-largefile option.
If you use this macro, check that your program works even when
off_t
is wider thanlong int
, since this is common when large-file support is enabled. For example, it is not correct to print an arbitraryoff_t
valueX
withprintf ("%ld", (long int) X)
.The LFS introduced the
fseeko
andftello
functions to replace their C counterpartsfseek
andftell
that do not useoff_t
. Take care to useAC_FUNC_FSEEKO
to make their prototypes available when using them and large-file support is enabled.