System Services
===============
The following macros check for operating system services or
capabilities.
- Macro: AC_PATH_X
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' on a
trivial `Imakefile' and examining the `Makefile' that it produces.
If that fails (such as if `xmkmf' is not present), look for them
in several directories where they often reside. If either method
is successful, set the shell variables `x_includes' and
`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.
- Macro: AC_PATH_XTRA
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
to `X_LIBS'. Define `X_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 variable `X_PRE_LIBS'.
- Macro: AC_SYS_INTERPRETER
Check whether the system supports starting scripts with a line of
the form `#! /bin/csh' 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 will be set to `yes'
if the system supports `#!', `no' if not.
- Macro: AC_SYS_LARGEFILE
Arrange for large-file support(1). 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 longer than `long', since this is common when
large-file support is enabled. For example, it is not correct to
print an arbitrary `off_t' value `X' with `printf ("%ld", (long)
X)'.
- Macro: AC_SYS_LONG_FILE_NAMES
If the system supports file names longer than 14 characters, define
`HAVE_LONG_FILE_NAMES'.
- Macro: AC_SYS_POSIX_TERMIOS
Check to see if POSIX termios headers and functions are available
on the system. If so, set the shell variable
`am_cv_sys_posix_termios' to `yes'. If not, set the variable to
`no'.
---------- Footnotes ----------
(1) large-file support,
<http://www.sas.com/standards/large.file/x_open.20Mar96.html>.