This module provides additional operations on files. This covers both
more obscure and possible non-portable low-level operations and
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.
- 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
now to indicate the current time. Defined options
- 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
link()) or removing (
Below are some example queries. The first retrieves the
access-time, while the second sets the last-modified time to the
?- set_time_file(foo, [access(Access)], ).
?- set_time_file(foo, , [modified(now)]).
- 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
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.
- relative_file_name(+Path:atom, +RelTo:atom, -RelPath:atom) is det
- relative_file_name(-Path:atom, +RelTo:atom, +RelPath:atom) is det
- 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:
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
- - This predicate is defined as a syntactical operation.
- directory_file_path(+Directory, +File, -Path) is det
- directory_file_path(?Directory, ?File, +Path) is det
- True when Path is the full path-name for File in Dir. This is
atom_concat(Directory, File, Path), but it ensures
there is exactly one / between the two parts. Notes:
- directory_member(+Directory, -Member, +Options) is nondet
- True when Member is a path inside Directory. Options defined are:
false), recurse into subdirectories
true (default), follow symbolic links.
- See absolute_file_name/3.
- Only return entries whose extension appears in List.
- How to handle errors. One of
warning. Errors notably happen if a directory is
unreadable or a link points nowhere.
- Only return entries with Access
- Only return files that match GlobPattern.
- Exclude files matching GlobPattern.
- Do not recurse into directories matching GlobPattern.
true (default), also return hidden files.
This predicate is safe against cycles introduced by symbolic links
The idea for a non-deterministic file search predicate comes from
- copy_file(+From, +To) is det
- Copy a file into a new file or directory. The data is copied as
- make_directory_path(+Dir) is det
- Create Dir and all required components (like mkdir -p). Can
raise various file-specific exceptions.
- copy_directory(+From, +To) is det
- 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.
- delete_directory_and_contents(+Dir) is det
- 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!
- delete_directory_contents(+Dir) is det
- 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
- chmod(+File, +Spec) is det
- Set the mode of the target file. Spec is one of
a plain Mode, which adds new permissions, revokes permissions or
sets the exact permissions. Mode itself is an integer, a POSIX
mode name or a list of POSIX mode names. Defines names are
svtx and the all names defined by the regular expression
[ugo]*[rwx]*. Specifying none of "ugo" is the same as specifying
all of them. For example, to make a file executable for the owner
(user) and group, we can use:
?- chmod(myfile, +ugx).