std::filesystem::rename (3) - Linux Manuals

std::filesystem::rename: std::filesystem::rename

NAME

std::filesystem::rename - std::filesystem::rename

Synopsis

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, (since C++17)
const std::filesystem::path& new_p,
std::error_code& ec) noexcept;

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);
  }