3 library(filesex): 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.

[det]set_time_file(+File, -OldTimes, +NewTimes)

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:

access(Time)

Describes the time of last access of the file. This value can be read and written.

modified(Time)

Describes the time the contents of the file was last modified. This value can be read and written.

changed(Time)

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)]).

[det]link_file(+OldPath, +NewPath, +Type)

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 unerlying filesystem must support links. This requires NTFS. Second, symbolic links are only supported in Vista and later.

Errors

domain_error(link_type, Type) if the requested link-type is unknown or not supported on the target OS.

[det]relative_file_name(+Path:atom, +RelTo:atom, -RelPath:atom)

[det]relative_file_name(-Path:atom, +RelTo:atom, +RelPath:atom)

True when RelPath is Path, relative to RelTo. 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'.

All	paths must be in canonical POSIX notation, i.e., using / to separate segments in the path. See prolog_to_os_filename/2.

bug

This predicate is defined as a syntactical operation.

[det]directory_file_path(+Directory, +File, -Path)

[det]directory_file_path(?Directory, ?File, +Path)

True when Path is the full path-name for File in Dir. This is comparable to atom_concat(Directory, File, Path), but it ensures there is exactly one / between the two parts. Notes:

• In mode (+,+,-), if File is given and absolute, Path is unified to File.
• Mode (-,-,+) uses file_directory_name/2 and file_base_name/2

[det]copy_file(From, To)

Copy a file into a new file or directory. The data is copied as binary data.

[det]make_directory_path(+Dir)

Create Dir and all required components (like mkdir -p). Can raise various file-specific exceptions.

[det]copy_directory(+From, +To)

Copy the contents of the directory From to To (recursively). If To is the name of an existing directory, the contents of From are copied into To. I.e., no subdirectory using the basename of From is created.

[det]delete_directory_and_contents(+Dir)

Recursively remove the directory Dir and its contents. If Dir is a symbolic link or symbolic links inside Dir are encountered, the links are removed rather than their content. Use with care!

[det]delete_directory_contents(+Dir)

Remove all content from directory Dir, without removing Dir itself. Similar to delete_directory_and_contents/2, if symbolic links are encountered in Dir, the links are removed rather than their content.