std::filesystem::rename

C++

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Technical Specifications

Filesystem library

Classes
filesystem::path filesystem::filesystem_error filesystem::directory_entry filesystem::directory_iterator filesystem::recursive_directory_iterator filesystem::file_status	filesystem::space_info filesystem::file_type filesystem::perms filesystem::perm_options filesystem::copy_options filesystem::directory_options filesystem::file_time_type
Functions
filesystem::absolute filesystem::canonicalfilesystem::weakly_canonical filesystem::relativefilesystem::proximate filesystem::copy filesystem::copy_file filesystem::copy_symlink filesystem::create_directory filesystem::create_directories filesystem::create_hard_link filesystem::create_symlink filesystem::create_directory_symlink filesystem::current_path	filesystem::exists filesystem::equivalent filesystem::file_size filesystem::hard_link_count filesystem::last_write_time filesystem::permissions filesystem::read_symlink filesystem::remove filesystem::remove_all filesystem::rename filesystem::resize_file filesystem::space filesystem::status filesystem::symlink_status filesystem::temp_directory_path
File types
filesystem::is_block_file filesystem::is_character_file filesystem::is_directory filesystem::is_empty filesystem::status_known	filesystem::is_fifo filesystem::is_other filesystem::is_regular_file filesystem::is_socket filesystem::is_symlink

Defined in header <filesystem>
void rename(const std::filesystem::path& old_p, const std::filesystem::path& new_p); void rename(const std::filesystem::path& old_p, const std::filesystem::path& new_p, std::error_code& ec) noexcept;		(since C++17)

Moves or renames the filesystem object identified by old_p to new_p as if by the POSIX rename:

• If old_p is a non-directory file, then new_p must be one of:

• the same file as old_p or a hardlink to it: nothing is done in this case
• existing non-directory file: new_p is first deleted, then, without allowing other processes to observe new_p as deleted, the pathname new_p is linked to the file and old_p is unlinked from the file. Write permissions are required to both the directory that contains old_p and the directory that contains new_p.
• non-existing file in an existing directory: The pathname new_p is linked to the file and old_p is unlinked from the file. Write permissions are required to both the directory that contains old_p and the directory that contains new_p.

• If old_p is a directory, then new_p must be one of:

• the same directory as old_p or a hardlink to it: nothing is done in this case
• existing directory: new_p is deleted if empty on POSIX systems, but this may be an error on other systems. If not an error, then new_p is first deleted, then, without allowing other processes to observe new_p as deleted, the pathname new_p is linked to the directory and old_p is unlinked from the directory. Write permissions are required to both the directory that contains old_p and the directory that contains new_p.
• non-existing directory, not ending with a directory separator, and whose parent directory exists: The pathname new_p is linked to the directory and old_p is unlinked from the directory. Write permissions are required to both the directory that contains old_p and the directory that contains new_p.

• Symlinks are not followed: if old_p is a symlink, it is itself renamed, not its target. If new_p is an existing symlink, it is itself erased, not its target.

Rename fails if

• new_p ends with dot or with dot-dot
• new_p names a non-existing directory ending with a directory separator
• old_p is a directory which is an ancestor of new_p

Parameters

old_p	-	path to move or rename
new_p	-	target path for the move/rename operation
ec	-	out-parameter for error reporting in the non-throwing overload

Return value

(none)

Exceptions

The overload that does not take a std::error_code& parameter throws filesystem_error on underlying OS API errors, constructed with old_p as the first path argument, new_p as the second path argument, and the OS error code as the error code argument. The overload taking a std::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. Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.

Example

Run this code

#include <iostream>
#include <fstream>
#include <filesystem>
namespace fs = std::filesystem;
int main()
{
    fs::path p = fs::current_path() / "sandbox";
    fs::create_directories(p/"from");
    std::ofstream(p/"from/file1.txt").put('a');
    fs::create_directory(p/"to");

//    fs::rename(p/"from/file1.txt", p/"to/"); // error: to is a directory
    fs::rename(p/"from/file1.txt", p/"to/file2.txt"); // OK
//    fs::rename(p/"from", p/"to"); // error: to is not empty
    fs::rename(p/"from", p/"to/subdir"); // OK

    fs::remove_all(p);
}

See also

rename	renames a file (function)
removeremove_all (C++17)(C++17)	removes a file or empty directory removes a file or directory and all its contents, recursively (function)