NAME¶

std::experimental::filesystem::copy - std::experimental::filesystem::copy

Synopsis¶

Defined in header <experimental/filesystem>
void copy( const path& from, const path& to ); (1) (filesystem TS)
void copy( const path& from, const path& to, error_code& ec );
void copy( const path& from, const path& to, copy_options
options ); (2) (filesystem TS)
void copy( const path& from, const path& to, copy_options
options, error_code& ec );

Copies files and directories, with a variety of options

1) The default, equivalent to (2) with copy_options::none used as options
2) Copies the file or directory from to file or directory to, using the copy options
indicated by options. The behavior is undefined if there is more than one option in
any of the copy_options option group present in options (even in the copy_file
group, which is not relevant to copy)

The behavior is as follows:

* First, before doing anything else, obtains type and permissions of from by no
more than single call to status (or, if copy_options::skip_symlinks or
copy_options::create_symlinks are present in options, by a call to
symlink_status).
* If necessary, obtains the status of to the same way, by no more than a single
status or symlink_status call.
* If from does not exist, reports an error.
* If from and to are the same file as determined by equivalent(), reports an error
* If either from or to is not a regular file, a directory, or a symlink, as
determined by is_other, reports an error
* If from is a directory, but to is a regular file, reports an error
* If from is a symbolic link, then

* If copy_options::skip_symlink is present in options, does nothing.
* Otherwise, if to does not exist and copy_options::copy_symlinks is
present in options, then behaves as if copy_symlink(from, to)
* Otherwise, reports an error

* Otherwise, if from is a regular file, then

* If copy_options::directories_only is present in options, does nothing
* Otherwise, if copy_options::create_symlinks is present in options,
creates a symlink to to. Note: from must be an absolute path unless to
is in the current directory.
* Otherwise, if copy_options::create_hard_links is present in options,
creates a hard link to to
* Otherwise, if to is a directory, then behaves as if copy_file(from,
to/from.filename(), options) (creates a copy of from as a file in the
directory to)
* Otherwise, behaves as if copy_file(from, to, options) (copies the file)

* Otherwise, if from is a directory and either options has copy_options::recursive
or is copy_options::none,

* If to does not exist, first executes create_directory(to, from)
(creates the new directory with a copy of the old directory's
attributes)
* Then, whether to already existed or was just created, iterates over the
files contained in from as if by for (const directory_entry& x :
directory_iterator(from)) and for each directory entry, recursively
calls copy(x.path(), to/x.path().filename(), options | unspecified),
where unspecified is a special bit that has no other effect when set in
options. (The sole purpose of setting this bit is to prevent recursive
copying subdirectories if options is copy_options::none.)

* Otherwise does nothing

Parameters¶

from - path to the source file, directory, or symlink
to - path to the target file, directory, or symlink
ec - out-parameter for error reporting in the non-throwing overload

Return value¶

(none)

Exceptions¶

The overload that does not take a error_code& parameter throws filesystem_error on
underlying OS API errors, constructed with from as the first argument, to as the
second argument, and the OS error code as the error code argument. std::bad_alloc
may be thrown if memory allocation fails. The overload taking a error_code&
parameter sets it to the OS API error code if an OS API call fails, and executes
ec.clear() if no errors occur. This overload has
noexcept specification:
noexcept

Notes¶

The default behavior when copying directories is the non-recursive copy: the files
are copied, but not the subdirectories:

// Given
// /dir1 contains /dir1/file1, /dir1/file2, /dir1/dir2
// and /dir1/dir2 contains /dir1/dir2/file3
// After
std::experimental::filesystem::copy("/dir1", "/dir3");
// /dir3 is created (with the attributes of /dir1)
// /dir1/file1 is copied to /dir3/file1
// /dir1/file2 is copied to /dir3/file2

While with copy_options::recursive, the subdirectories are also copied, with their
content, recursively.

// ...but after
std::experimental::filesystem::copy("/dir1", "/dir3", copy_options::recursive);
// /dir3 is created (with the attributes of /dir1)
// /dir1/file1 is copied to /dir3/file1
// /dir1/file2 is copied to /dir3/file2
// /dir3/dir2 is created (with the attributes of /dir1/dir2)
// /dir1/dir2/file3 is copied to /dir3/dir2/file3

Example¶

// Run this code

#include <iostream>
#include <fstream>
#include <experimental/filesystem>
namespace fs = std::experimental::filesystem;

int main()
{
fs::create_directories("sandbox/dir/subdir");
std::ofstream("sandbox/file1.txt").put('a');
fs::copy("sandbox/file1.txt", "sandbox/file2.txt"); // copy file
fs::copy("sandbox/dir", "sandbox/dir2"); // copy directory (non-recursive)
// sandbox holds 2 files and 2 directories, one of which has a subdirectory
// sandbox/file1.txt
// sandbox/file2.txt
// sandbox/dir2
// sandbox/dir
// sandbox/dir/subdir
fs::copy("sandbox", "sandbox/copy", fs::copy_options::recursive);
// sandbox/copy holds copies of the above files and subdirectories
fs::remove_all("sandbox");
}

See also¶

copy_options specifies semantics of copy operations
(enum)
copy_symlink copies a symbolic link
(function)
copy_file copies file contents
(function)