IFP is for Linux only, and requires a C99 compiler with GNU gcc extensions.  It
may be 64-bit clean, but is not thread-safe.

There are several source distribution files.  Core IFP is in ifp-1.4-core.tgz,
while ifp-1.4-resources.tgz contains all of the additional third-party code
needed to build Glk and interpreter plugins, and some sample games.  For full
IFP builds, unpack both into the same directory.

Alternatively, obtain a copy of ifp-1.4.tgz, which contains both core IFP and
third-party code combined.

To build, run 'configure' and then 'make'.  IFP offers the usual options to
'configure', and the expected 'make' targets.

Run games with the new IFP build using commands such as

    cd src/ifp
    IF_PLUGIN_PATH=".:../../third_party/plugins" ifpe -glk xglk \
    ../../third_party/distributed/weather.z5

This sets a value for the variable IF_PLUGIN_PATH, used by the IFP libraries
when deciding where to look for plugins, requests the xglk display library,
then runs a sample game from the IFP resources.

Some other things to try are

    cd src/ifp
    IF_PLUGIN_PATH=".:../../third_party/plugins" ifpe -glk cheapglk \
    ../../third_party/derivatives/bugged.zip

    cd src/ifp
    IF_PLUGIN_PATH=".:../../third_party/plugins" legion -glk glkterm \
    http://www.ifarchive.org/if-archive/games/zcode/curses.z5

Once installed, you can set permanent values for IF_PLUGIN_PATH and for
IFP_GLK_LIBRARIES, or configure IFP using your .ifprc file.

The IFP_TRACE environment variable turns on debug output for IFP.  Set it to
'all' to view all trace information, or to a space-separated list of modules
to select traces from individual source modules.