SWI-Prolog -- absolute_file

Availability:built-in

absolute_file_name(+Spec, -Absolute, +Options)

Convert the given file specification into an absolute path. Spec is a term Alias(Relative) (e.g., (library(lists)), a relative filename or an absolute filename. The primary intention of this predicate is to resolve files specified as Alias(Relative), which use file_search_path/2 to look up the possibilities for Alias. With the default options no file system check is performed and the alias-resolved path is returned as is; in particular, it may name a directory. To require a non-directory pass file_type(regular), file_type(prolog), or an access(Mode) other than none. Pass file_type(directory) to look up directories. For example, when the library holds both a chr.pl file and a chr directory, absolute_file_name(library(chr), F) resolves to the directory, while absolute_file_name(library(chr), F, [file_type(prolog)]) resolves to chr.pl. The result always uses the directory separator /; if the operating system uses something different, SWI-Prolog converts the file name before it makes an OS call. If you need the filename in the OS's preferred form, use prolog_to_os_filename/2. Supported Options are:

extensions(ListOfExtensions): List of file extensions to try. Default is [’’]. For each extension, absolute_file_name/3 will first add the extension and then verify the conditions imposed by the other options. If the condition fails, the next extension on the list is tried. Extensions may be specified both as .ext or plain ext.
relative_to(+FileOrDir): Resolve the path relative to the given directory or the directory holding the given file. Without this option, paths are resolved relative to the working directory (see working_directory/2) or, if Spec is atomic and absolute_file_name/[2,3] is executed in a directive, it uses the current source file as reference. Note that a directive using initialization/1 is executed after loading the file. This implies that such paths are resolved relative to the working directory for the toplevel file and relative to the file loading the file holding the initialization/1 directive otherwise.
Up to version 9.3.9, the system tried both the directory holding the current source and the current working directory.
access(Mode): Imposes the condition access_file(File, Mode). Mode is one of read, write, append, execute, search, exist or none. See also access_file/2. The default is none which, if file_type is not specified as directory or regular, returns absolute file names that result from expanding aliases without inspecting the actual file system.
file_type(Type): Defines extensions. Current mapping: txt implies [’’], prolog implies [’.pl’,’’], executable implies [’.so’,’’] and qlf implies [’.qlf’,’’]. The Type directory implies [’’] and causes this predicate to generate (only) directories. The Type regular is the opposite of directory and is the default if no file type is specified and the requested access is not none. Since the default access is none, file_type(regular) is not implied by default; see the introduction above.
The file type source is an alias for prolog for compatibility with SICStus Prolog. See also prolog_file_type/2.
file_errors(fail/error): If error (default), throw an existence_error exception if the file cannot be found. If fail, stay silent.^{160Silent operation was the
default up to version 3.2.6.}
solutions(first/all): If first (default), the predicate leaves no choice point. Otherwise a choice point will be left and backtracking may yield more solutions.
expand(Boolean): If true (default is false) and Spec is atomic, call expand_file_name/2 followed by member/2 on Spec before proceeding. This is a SWI-Prolog extension intended to minimise porting effort after SWI-Prolog stopped expanding environment variables and the ~ by default. This option should be considered deprecated. In particular the use of wildcard patterns such as * should be avoided.

The Prolog flag verbose_file_search can be set to true to help debugging Prolog's search for files. See also file_search_path/2.

This predicate is derived from Quintus Prolog. In Quintus Prolog, the argument order was absolute_file_name(+Spec, +Options, -Path). The argument order has been changed for compatibility with ISO and SICStus. The Quintus argument order is still accepted.