RENAME(2)		   Linux Programmer's Manual		     RENAME(2)



NAME
       rename, renameat, renameat2 - change the name or location of a file

SYNOPSIS
       #include <stdio.h>

       int rename(const char *oldpath, const char *newpath);

       #include <fcntl.h>	    /* Definition of AT_* constants */
       #include <stdio.h>

       int renameat(int olddirfd, const char *oldpath,
		    int newdirfd, const char *newpath);

       int renameat2(int olddirfd, const char *oldpath,
		     int newdirfd, const char *newpath, unsigned int flags);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       renameat():
	   Since glibc 2.10:
	       _POSIX_C_SOURCE >= 200809L
	   Before glibc 2.10:
	       _ATFILE_SOURCE

DESCRIPTION
       rename()	 renames  a  file,  moving it between directories if required.
       Any other hard links to the file (as created using link(2))  are	 unaf-
       fected.	Open file descriptors for oldpath are also unaffected.

       Various restrictions determine whether or not the rename operation suc-
       ceeds: see ERRORS below.

       If newpath already exists, it will  be  atomically  replaced,  so  that
       there is no point at which another process attempting to access newpath
       will find it missing.  However, there will  probably  be	 a  window  in
       which both oldpath and newpath refer to the file being renamed.

       If  oldpath  and	 newpath are existing hard links referring to the same
       file, then rename() does nothing, and returns a success status.

       If newpath exists but the operation fails  for  some  reason,  rename()
       guarantees to leave an instance of newpath in place.

       oldpath can specify a directory.	 In this case, newpath must either not
       exist, or it must specify an empty directory.

       If oldpath refers to a symbolic link, the link is renamed;  if  newpath
       refers to a symbolic link, the link will be overwritten.

   renameat()
       The  renameat()	system	call  operates	in  exactly  the  same	way as
       rename(), except for the differences described here.

       If the pathname given in oldpath is relative, then  it  is  interpreted
       relative	 to  the directory referred to by the file descriptor olddirfd
       (rather than relative to the current working directory of  the  calling
       process, as is done by rename() for a relative pathname).

       If oldpath is relative and olddirfd is the special value AT_FDCWD, then
       oldpath is interpreted relative to the current working directory of the
       calling process (like rename()).

       If oldpath is absolute, then olddirfd is ignored.

       The interpretation of newpath is as for oldpath, except that a relative
       pathname is interpreted relative to the directory referred  to  by  the
       file descriptor newdirfd.

       See openat(2) for an explanation of the need for renameat().

   renameat2()
       renameat2()  has an additional flags argument.  A renameat2() call with
       a zero flags argument is equivalent to renameat().

       The flags argument is a bit mask consisting of zero or more of the fol-
       lowing flags:

       RENAME_EXCHANGE
	      Atomically  exchange  oldpath  and newpath.  Both pathnames must
	      exist but may be of different types (e.g., one could be  a  non-
	      empty directory and the other a symbolic link).

       RENAME_NOREPLACE
	      Don't  overwrite newpath of the rename.  Return an error if new-
	      path already exists.

	      RENAME_NOREPLACE	  can't	   be	 employed    together	  with
	      RENAME_EXCHANGE.

       RENAME_WHITEOUT (since Linux 3.18)
	      This  operation  makes  sense  only for overlay/union filesystem
	      implementations.

	      Specifying RENAME_WHITEOUT creates a "whiteout"  object  at  the
	      source  of the rename at the same time as performing the rename.
	      The whole operation is atomic, so that if	 the  rename  succeeds
	      then the whiteout will also have been created.

	      A	  "whiteout"   is  an  object  that  has  special  meaning  in
	      union/overlay filesystem constructs.  In these constructs,  mul-
	      tiple  layers  exist  and	 only the top one is ever modified.  A
	      whiteout on an upper layer will effectively hide a matching file
	      in  the  lower  layer,  making  it  appear as if the file didn't
	      exist.

	      When a file that exists on the lower layer is renamed, the  file
	      is  first copied up (if not already on the upper layer) and then
	      renamed on the upper, read-write layer.  At the same  time,  the
	      source file needs to be "whiteouted" (so that the version of the
	      source file in the lower	layer  is  rendered  invisible).   The
	      whole operation needs to be done atomically.

	      When  not	 part  of  a  union/overlay, the whiteout appears as a
	      character device with a {0,0} device number.

	      RENAME_WHITEOUT requires	the  same  privileges  as  creating  a
	      device node (i.e., the CAP_MKNOD capability).

	      RENAME_WHITEOUT can't be employed together with RENAME_EXCHANGE.

	      RENAME_WHITEOUT requires support from the underlying filesystem.
	      Among the filesystems that provide that support are shmem (since
	      Linux 3.18), ext4 (since Linux 3.18), and XFS (since Linux 4.1).

RETURN VALUE
       On  success,  zero is returned.	On error, -1 is returned, and errno is
       set appropriately.

ERRORS
       EACCES Write permission is denied for the directory containing  oldpath
	      or  newpath,  or,	 search	 permission  is	 denied for one of the
	      directories in the path prefix of oldpath or newpath, or oldpath
	      is  a  directory	and does not allow write permission (needed to
	      update the ..  entry).  (See also path_resolution(7).)

       EBUSY  The rename fails because oldpath or newpath is a directory  that
	      is in use by some process (perhaps as current working directory,
	      or as root directory, or because it was open for reading) or  is
	      in  use  by  the	system (for example as mount point), while the
	      system considers this an error.  (Note that there is no require-
	      ment  to return EBUSY in such cases--there is nothing wrong with
	      doing the rename anyway--but it is allowed to  return  EBUSY  if
	      the system cannot otherwise handle such situations.)

       EDQUOT The  user's  quota  of  disk  blocks  on the filesystem has been
	      exhausted.

       EFAULT oldpath or newpath points outside your accessible address space.

       EINVAL The new pathname contained a path prefix of the  old,  or,  more
	      generally,  an  attempt was made to make a directory a subdirec-
	      tory of itself.

       EISDIR newpath is an existing directory, but oldpath is	not  a	direc-
	      tory.

       ELOOP  Too many symbolic links were encountered in resolving oldpath or
	      newpath.

       EMLINK oldpath already has the maximum number of links to it, or it was
	      a directory and the directory containing newpath has the maximum
	      number of links.

       ENAMETOOLONG
	      oldpath or newpath was too long.

       ENOENT The link named by oldpath does not exist; or, a directory compo-
	      nent  in	newpath	 does  not exist; or, oldpath or newpath is an
	      empty string.

       ENOMEM Insufficient kernel memory was available.

       ENOSPC The device containing the file has no room for the new directory
	      entry.

       ENOTDIR
	      A component used as a directory in oldpath or newpath is not, in
	      fact, a directory.  Or, oldpath  is  a  directory,  and  newpath
	      exists but is not a directory.

       ENOTEMPTY or EEXIST
	      newpath is a nonempty directory, that is, contains entries other
	      than "." and "..".

       EPERM or EACCES
	      The directory containing oldpath has the	sticky	bit  (S_ISVTX)
	      set  and	the process's effective user ID is neither the user ID
	      of the file to be deleted nor that of the	 directory  containing
	      it,  and the process is not privileged (Linux: does not have the
	      CAP_FOWNER capability); or newpath is an existing file  and  the
	      directory containing it has the sticky bit set and the process's
	      effective user ID is neither the user  ID	 of  the  file	to  be
	      replaced	nor  that  of  the  directory  containing  it, and the
	      process is not privileged (Linux: does not have  the  CAP_FOWNER
	      capability); or the filesystem containing pathname does not sup-
	      port renaming of the type requested.

       EROFS  The file is on a read-only filesystem.

       EXDEV  oldpath and newpath are not  on  the  same  mounted  filesystem.
	      (Linux  permits  a  filesystem to be mounted at multiple points,
	      but rename() does not work across different mount	 points,  even
	      if the same filesystem is mounted on both.)

       The   following	 additional   errors  can  occur  for  renameat()  and
       renameat2():

       EBADF  olddirfd or newdirfd is not a valid file descriptor.

       ENOTDIR
	      oldpath is relative and olddirfd is a file descriptor  referring
	      to  a  file  other  than a directory; or similar for newpath and
	      newdirfd

       The following additional errors can occur for renameat2():

       EEXIST flags contains RENAME_NOREPLACE and newpath already exists.

       EINVAL An invalid flag was specified in flags.

       EINVAL Both RENAME_NOREPLACE  and  RENAME_EXCHANGE  were	 specified  in
	      flags.

       EINVAL Both  RENAME_WHITEOUT  and  RENAME_EXCHANGE  were	 specified  in
	      flags.

       EINVAL The filesystem does not support one of the flags in flags.

       ENOENT flags contains RENAME_EXCHANGE and newpath does not exist.

       EPERM  RENAME_WHITEOUT was specified in flags, but the caller does  not
	      have the CAP_MKNOD capability.

VERSIONS
       renameat()  was	added  to  Linux in kernel 2.6.16; library support was
       added to glibc in version 2.4.

       renameat2() was added to Linux in kernel 3.15.

CONFORMING TO
       rename(): 4.3BSD, C89, C99, POSIX.1-2001, POSIX.1-2008.

       renameat(): POSIX.1-2008.

       renameat2() is Linux-specific.

NOTES
   Glibc notes
       On older kernels where renameat() is  unavailable,  the	glibc  wrapper
       function	 falls	back to the use of rename().  When oldpath and newpath
       are relative pathnames, glibc constructs pathnames based	 on  the  sym-
       bolic  links  in	 /proc/self/fd	that  correspond  to  the olddirfd and
       newdirfd arguments.

BUGS
       On NFS filesystems, you can not assume that if  the  operation  failed,
       the  file was not renamed.  If the server does the rename operation and
       then crashes, the retransmitted RPC which will be  processed  when  the
       server  is  up  again causes a failure.	The application is expected to
       deal with this.	See link(2) for a similar problem.

SEE ALSO
       mv(1), chmod(2), link(2),  symlink(2),  unlink(2),  path_resolution(7),
       symlink(7)

COLOPHON
       This  page  is  part of release 4.10 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest	  version     of     this    page,    can    be	   found    at
       https://www.kernel.org/doc/man-pages/.



Linux				  2016-10-08			     RENAME(2)