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 the
environment variable) on a trivial Imakefile and examining the
makefile that it produces. Setting
XMKMF to ‘false’
disables this method.
If this method fails to find the X Window System,
looks for the files in several directories where they often reside.
If either method is successful, set the shell variables
x_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 variable
X_CFLAGS, and the X linker flags
X_DISPLAY_MISSING if X is not
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
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 variable
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
_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 than
long int, since this is common when
large-file support is enabled. For example, it is not correct to print
(long int) X).
The LFS introduced the
ftello functions to
replace their C counterparts
ftell that do not
off_t. Take care to use
AC_FUNC_FSEEKO to make their
prototypes available when using them and large-file support is
If the system supports file names longer than 14 characters, define
Check to see if the Posix termios headers and functions are available on the
system. If so, set the shell variable
‘yes’. If not, set the variable to ‘no’.