Executables embedding SWI-Prolog should be able to find the ‘home’
directory of the development environment unless a self-contained saved
state has been added to the executable (see qsave_program/[1,2]
and section 12.5).
If Prolog starts up, it will try to locate the development
environment. To do so, it will try the following steps until one
succeeds:
- If the --home=DIR is provided, use this.
- If the environment variable
SWI_HOME_DIR is defined and
points to an existing directory, use this.
- If the environment variable
SWIPL is defined and points
to an existing directory, use this.
- Locate the primary executable or (Windows only) a component (module)
thereof and check whether the parent directory of the directory holding
this file contains the file
swipl. If so, this file
contains the (relative) path to the home directory. If this directory
exists, use this. This is the normal mechanism used by the binary
distribution.
- If the precompiled path exists, use it. This is only useful for a
source installation.
If all fails and there is no state attached to the executable or
provided Windows module (see PL_initialise()),
SWI-Prolog gives up. If a state is attached, the current working
directory is used.
The file_search_path/2
alias swi is set to point to the home directory located.
