The program chpl, may be used to manipulate the header of a SWI-Prolog bootfile or state created with qsave_program/[1,2].
It will be used most commonly by the installer of a SWI-Prolog runtime application to specify the path to the emulator. If the end-user decided to install the SWI-Prolog runtime environment in
/usr/local/lib/rt-pl-2.1.4
the gnat application can be told to use this emulator using:
% /usr/local/lib/rtpl-2.1.4/bin/chpl -e /usr/local/lib/rt-pl-2.1.4/bin/pl gnat
Now, gnat may be installed in any public or private directory for binaries.