### 2.3 Building sources using Automake

It is much easier if you use GNU Automake instead of writing your own Makefiles. If you do that, you do not have to worry about finding and invoking the `libgcrypt-config` script at all. Libgcrypt provides an extension to Automake that does all the work for you.

Macro: AM_PATH_LIBGCRYPT ([minimum-version], [action-if-found], [action-if-not-found]) ¶

  Check whether Libgcrypt (at least version minimum-version, if given) exists on the host system. If it is found, execute action-if-found, otherwise do action-if-not-found, if given.

  Additionally, the function defines `LIBGCRYPT_CFLAGS` to the flags needed for compilation of the program to find the `gcrypt.h` header file, and `LIBGCRYPT_LIBS` to the linker flags needed to link the program to the Libgcrypt library. If the used helper script does not match the target type you are building for a warning is printed and the string `libgcrypt` is appended to the variable `gpg_config_script_warn`.

  This macro searches for `libgcrypt-config` along the PATH. If you are cross-compiling, it is useful to set the environment variable `SYSROOT` to the top directory of your target. The macro will then first look for the helper program in the `bin` directory below that top directory. An absolute directory name must be used for `SYSROOT`. Finally, if the configure command line option `--with-libgcrypt-prefix` is used, only its value is used for the top directory below which the helper script is expected.

You can use the defined Autoconf variables like this in your `Makefile.am`:

    AM_CPPFLAGS = $(LIBGCRYPT_CFLAGS)
    LDADD = $(LIBGCRYPT_LIBS)