Provided by: manpages-posix-dev_2017a-2_all 
PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface
may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface
may not be implemented on Linux.
NAME
rename, renameat — rename file
SYNOPSIS
#include <stdio.h>
int rename(const char *old, const char *new);
#include <fcntl.h>
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.1‐2017 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 directory entries for the same
existing file, rename() shall return successfully 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 directory. 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 threads 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 containing 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 directory. 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 directory.
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 symbolic 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 pathname. 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 happens only relative to the directory associated with newfd. If the
access mode of the open file description associated with the file descriptor is not O_SEARCH, the
function shall check whether directory searches are permitted using the current permissions of the
directory underlying the file descriptor. If the access mode is 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. Otherwise, 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 permissions; 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 component 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 resolution 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 directory; 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 pathname 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> character, and ends with one or more trailing <slash> characters.
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.1‐2017, Section 4.3, 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.1‐2017,
Section 4.3, 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 systems and the implementation does not
support links between file systems.
In addition, the renameat() function shall fail if:
EACCES The access mode of the open file description associated with oldfd or newfd is not 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 resolution 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 timestamp 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 directories 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.1‐2017, Section 4.3, Directory Protection, <fcntl.h>, <stdio.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. 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.opengroup.org/unix/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.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 RENAME(3POSIX)