|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | CONFORMING TO | NOTES | BUGS | SEE ALSO | COLOPHON |
|
RENAME(2) Linux Programmer's Manual RENAME(2)
rename, renameat, renameat2 - change the name or location of a file
#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);
Note: There is no glibc wrapper for renameat2(); see NOTES.
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
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).
On success, zero is returned. On error, -1 is returned, and errno is
set appropriately.
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.
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.
rename(): 4.3BSD, C89, C99, POSIX.1-2001, POSIX.1-2008.
renameat(): POSIX.1-2008.
renameat2() is Linux-specific.
Glibc does not provide a wrapper for the renameat2() system call;
call it using syscall(2).
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.
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.
mv(1), chmod(2), link(2), symlink(2), unlink(2), path_resolution(7),
symlink(7)
This page is part of release 4.15 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 2017-09-15 RENAME(2)
Pages that refer to this page: fcntl(2), link(2), open(2), rmdir(2), symlink(2), syscalls(2), unlink(2), remove(3), cpuset(7), inotify(7), signal-safety(7), symlink(7), lsof(8)
Copyright and license for this manual page
|
HTML rendering created 2018-02-02 by Michael Kerrisk, author of The Linux Programming Interface, maintainer of the Linux man-pages project. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH.
|
|