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
   unaffected.  Open file descriptors for oldpath are also unaffected.

   Various  restrictions  determine  whether  or  not the rename operation
   succeeds: 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
   following 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
          newpath 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,
          multiple  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
          requirement 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
          subdirectory of itself.

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

   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
          component  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
          support 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
   symbolic  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 4.09 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/.

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