PublicShow -- Extended operations on files

This module provides additional operations on files. This covers both more obscure and possible non-portable low-level operations and high-level utilities.

Using these Prolog primitives is typically to be preferred over using operating system primitives through shell/1 or process_create/3 because (1) there are no potential file name quoting issues, (2) there is no dependency on operating system commands and (3) using the implementations from this library is usually faster.

Source set_time_file(+File, -OldTimes, +NewTimes) is det
Query and set POSIX time attributes of a file. Both OldTimes and NewTimes are lists of option-terms. Times are represented in SWI-Prolog's standard floating point numbers. New times may be specified as now to indicate the current time. Defined options are:
Describes the time of last access of the file. This value can be read and written.
Describes the time the contents of the file was last modified. This value can be read and written.
Describes the time the file-structure itself was changed by adding (link()) or removing (unlink()) names.

Below are some example queries. The first retrieves the access-time, while the second sets the last-modified time to the current time.

?- set_time_file(foo, [access(Access)], []).
?- set_time_file(foo, [], [modified(now)]).
Source link_file(+OldPath, +NewPath, +Type) is det
Create a link in the filesystem from NewPath to OldPath. Type defines the type of link and is one of hard or symbolic.

With some limitations, these functions also work on Windows. First of all, the underlying filesystem must support links. This requires NTFS. Second, symbolic links are only supported in Vista and later.

- domain_error(link_type, Type) if the requested link-type is unknown or not supported on the target OS.
Source relative_file_name(+Path:atom, +RelToFile:atom, -RelPath:atom) is det
relative_file_name(-Path:atom, +RelToFile:atom, +RelPath:atom) is det
True when RelPath is Path, relative to the file RelToFile. Path and RelTo are first handed to absolute_file_name/2, which makes the absolute and canonical. Below are two examples:
?- relative_file_name('/home/janw/nice',
                      '/home/janw/deep/dir/file', Path).
Path = '../../nice'.

?- relative_file_name(Path, '/home/janw/deep/dir/file', '../../nice').
Path = '/home/janw/nice'.

Add a terminating / to get a path relative to a directory, e.g.

?- relative_file_name('/home/janw/deep/dir/file', './', Path).
Path = 'deep/dir/file'.
All- paths must be in canonical POSIX notation, i.e., using / to separate segments in the path. See prolog_to_os_filename/2.
- It would probably have been cleaner to use a directory as second argument. We can not do such dynamically as this predicate is defined as a syntactical operation, which implies it may be used for non-existing paths and URLs.

Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

Source delete_directory_and_contents(Arg1)
Source delete_directory_contents(Arg1)
Source copy_directory(Arg1, Arg2)
Source make_directory_path(Arg1)
Source directory_member(Arg1, Arg2, Arg3)
Source copy_file(Arg1, Arg2)
Source directory_file_path(Arg1, Arg2, Arg3)
Source chmod(Arg1, Arg2)