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This manual page is part of the POSIX Programmer's Manual. The Linux
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Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
NAME
rename, renameat -- rename file relative to directory file descriptor
SYNOPSIS
#include <stdio.h>
int rename(const char *old, const char *new);
int renameat(int oldfd, const char *old, int newfd,
const char *new);
DESCRIPTION
For rename(): The functionality described on this reference page is
aligned with the ISO C standard. Any conflict between the requirements
described here and the ISO C standard is unintentional. This volume of
POSIX.1-2008 defers to the ISO C standard.
The rename() function shall change the name of a file. The old argument
points to the pathname of the file to be renamed. The new argument
points to the new pathname of the file. If the new argument does not
resolve to an existing directory entry for a file of type directory and
the new argument contains at least one non-<slash> character and ends
with one or more trailing <slash> characters after all symbolic links
have been processed, rename() shall fail.
If either the old or new argument names a symbolic link, rename() shall
operate on the symbolic link itself, and shall not resolve the last
component of the argument. If the old argument and the new argument
resolve to either the same existing directory entry or different direc-
tory entries for the same existing file, rename() shall return success-
fully and perform no other action.
If the old argument points to the pathname of a file that is not a
directory, the new argument shall not point to the pathname of a direc-
tory. If the link named by the new argument exists, it shall be removed
and old renamed to new. In this case, a link named new shall remain
visible to other processes throughout the renaming operation and refer
either to the file referred to by new or old before the operation
began. Write access permission is required for both the directory con-
taining old and the directory containing new.
If the old argument points to the pathname of a directory, the new
argument shall not point to the pathname of a file that is not a direc-
tory. If the directory named by the new argument exists, it shall be
removed and old renamed to new. In this case, a link named new shall
exist throughout the renaming operation and shall refer either to the
directory referred to by new or old before the operation began. If new
names an existing directory, it shall be required to be an empty direc-
tory.
If either pathname argument refers to a path whose final component is
either dot or dot-dot, rename() shall fail.
If the old argument points to a pathname of a symbolic link, the sym-
bolic link shall be renamed. If the new argument points to a pathname
of a symbolic link, the symbolic link shall be removed.
The old pathname shall not name an ancestor directory of the new path-
name. Write access permission is required for the directory containing
old and the directory containing new. If the old argument points to
the pathname of a directory, write access permission may be required
for the directory named by old, and, if it exists, the directory named
by new.
If the link named by the new argument exists and the file's link count
becomes 0 when it is removed and no process has the file open, the
space occupied by the file shall be freed and the file shall no longer
be accessible. If one or more processes have the file open when the
last link is removed, the link shall be removed before rename()
returns, but the removal of the file contents shall be postponed until
all references to the file are closed.
Upon successful completion, rename() shall mark for update the last
data modification and last file status change timestamps of the parent
directory of each file.
If the rename() function fails for any reason other than [EIO], any
file named by new shall be unaffected.
The renameat() function shall be equivalent to the rename() function
except in the case where either old or new specifies a relative path.
If old is a relative path, the file to be renamed is located relative
to the directory associated with the file descriptor oldfd instead of
the current working directory. If new is a relative path, the same hap-
pens only relative to the directory associated with newfd. If the file
descriptor was opened without O_SEARCH, the function shall check
whether directory searches are permitted using the current permissions
of the directory underlying the file descriptor. If the file descriptor
was opened with O_SEARCH, the function shall not perform the check.
If renameat() is passed the special value AT_FDCWD in the oldfd or
newfd parameter, the current working directory shall be used in the
determination of the file for the respective path parameter.
RETURN VALUE
Upon successful completion, the rename() function shall return 0. Oth-
erwise, it shall return -1, errno shall be set to indicate the error,
and neither the file named by old nor the file named by new shall be
changed or created.
Upon successful completion, the renameat() function shall return 0.
Otherwise, it shall return -1 and set errno to indicate the error.
ERRORS
The rename() and renameat() functions shall fail if:
EACCES A component of either path prefix denies search permission; or
one of the directories containing old or new denies write per-
missions; or, write permission is required and is denied for a
directory pointed to by the old or new arguments.
EBUSY The directory named by old or new is currently in use by the
system or another process, and the implementation considers this
an error.
[EEXIST] or [ENOTEMPTY]
The link named by new is a directory that is not an empty
directory.
EINVAL The old pathname names an ancestor directory of the new
pathname, or either pathname argument contains a final com-
ponent that is dot or dot-dot.
EIO A physical I/O error has occurred.
EISDIR The new argument points to a directory and the old argument
points to a file that is not a directory.
ELOOP A loop exists in symbolic links encountered during resolu-
tion of the path argument.
EMLINK The file named by old is a directory, and the link count of
the parent directory of new would exceed {LINK_MAX}.
ENAMETOOLONG
The length of a component of a pathname is longer than
{NAME_MAX}.
ENOENT The link named by old does not name an existing file, a
component of the path prefix of new does not exist, or
either old or new points to an empty string.
ENOSPC The directory that would contain new cannot be extended.
ENOTDIR A component of either path prefix names an existing file
that is neither a directory nor a symbolic link to a direc-
tory; or the old argument names a directory and the new
argument names a non-directory file; or the old argument
contains at least one non-<slash> character and ends with
one or more trailing <slash> characters and the last path-
name component names an existing file that is neither a
directory nor a symbolic link to a directory; or the old
argument names an existing non-directory file and the new
argument names a nonexistent file, contains at least one
non-<slash> character, and ends with one or more trailing
<slash> characters; or the new argument names an existing
non-directory file, contains at least one non-<slash> char-
acter, and ends with one or more trailing <slash> charac-
ters.
EPERM or EACCES
The S_ISVTX flag is set on the directory containing the
file referred to by old and the process does not satisfy
the criteria specified in the Base Definitions volume of
POSIX.1-2008, Section 4.2, Directory Protection with
respect to old; or new refers to an existing file, the
S_ISVTX flag is set on the directory containing this file,
and the process does not satisfy the criteria specified in
the Base Definitions volume of POSIX.1-2008, Section 4.2,
Directory Protection with respect to this file.
EROFS The requested operation requires writing in a directory on
a read-only file system.
EXDEV The links named by new and old are on different file sys-
tems and the implementation does not support links between
file systems.
In addition, the renameat() function shall fail if:
EACCES oldfd or newfd was not opened with O_SEARCH and the permissions
of the directory underlying oldfd or newfd respectively do not
permit directory searches.
EBADF The old argument does not specify an absolute path and the oldfd
argument is neither AT_FDCWD nor a valid file descriptor open
for reading or searching, or the new argument does not specify
an absolute path and the newfd argument is neither AT_FDCWD nor
a valid file descriptor open for reading or searching.
ENOTDIR
The old or new argument is not an absolute path and oldfd or
newfd, respectively, is a file descriptor associated with a non-
directory file.
The rename() and renameat() functions may fail if:
EBUSY The file named by the old or new arguments is a named STREAM.
ELOOP More than {SYMLOOP_MAX} symbolic links were encountered during
resolution of the path argument.
ENAMETOOLONG
The length of a pathname exceeds {PATH_MAX}, or pathname resolu-
tion of a symbolic link produced an intermediate result with a
length that exceeds {PATH_MAX}.
ETXTBSY
The file named by new exists and is the last directory entry to
a pure procedure (shared text) file that is being executed.
The following sections are informative.
EXAMPLES
Renaming a File
The following example shows how to rename a file named /home/cnd/mod1
to /home/cnd/mod2.
#include <stdio.h>
int status;
...
status = rename("/home/cnd/mod1", "/home/cnd/mod2");
APPLICATION USAGE
Some implementations mark for update the last file status change time-
stamp of renamed files and some do not. Applications which make use of
the last file status change timestamp may behave differently with
respect to renamed files unless they are designed to allow for either
behavior.
RATIONALE
This rename() function is equivalent for regular files to that defined
by the ISO C standard. Its inclusion here expands that definition to
include actions on directories and specifies behavior when the new
parameter names a file that already exists. That specification requires
that the action of the function be atomic.
One of the reasons for introducing this function was to have a means of
renaming directories while permitting implementations to prohibit the
use of link() and unlink() with directories, thus constraining links to
directories to those made by mkdir().
The specification that if old and new refer to the same file is
intended to guarantee that:
rename("x", "x");
does not remove the file.
Renaming dot or dot-dot is prohibited in order to prevent cyclical file
system paths.
See also the descriptions of [ENOTEMPTY] and [ENAMETOOLONG] in rmdir()
and [EBUSY] in unlink(). For a discussion of [EXDEV], see link().
The purpose of the renameat() function is to rename files in directo-
ries other than the current working directory without exposure to race
conditions. Any part of the path of a file could be changed in parallel
to a call to rename(), resulting in unspecified behavior. By opening
file descriptors for the source and target directories and using the
renameat() function it can be guaranteed that that renamed file is
located correctly and the resulting file is in the desired directory.
FUTURE DIRECTIONS
None.
SEE ALSO
link(), rmdir(), symlink(), unlink()
The Base Definitions volume of POSIX.1-2008, Section 4.2, Directory
Protection, <stdio.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri-
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker-
nel.org/doc/man-pages/reporting_bugs.html .
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