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NAME
rename - rename a file
SYNOPSIS
#include <stdio.h> int rename(const char *old, const char *new);
DESCRIPTION
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 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 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 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 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 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 new pathname shall not contain a path prefix that names old. 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 st_ctime and st_mtime fields 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.
RETURN VALUE
Upon successful completion, rename() shall return 0; otherwise, -1 shall be returned, 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.
ERRORS
The rename() function 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 new directory pathname contains a path prefix that names the old directory.
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 the old or new argument exceeds {PATH_MAX} or a pathname component is longer than
{NAME_MAX}.
ENOENT The link named by old does not name an existing file, 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 is not a directory; or the old argument names a directory and
new argument names a non-directory file.
EPERM or EACCES
The S_ISVTX flag is set on the directory containing the file referred to by old and the caller is
not the file owner, nor is the caller the directory owner, nor does the caller have appropriate
privileges; or new refers to an existing file, the S_ISVTX flag is set on the directory containing
this file, and the caller is not the file owner, nor is the caller the directory owner, nor does
the caller have appropriate privileges.
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.
The rename() function 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
As a result of encountering a symbolic link in resolution of the path argument, the length of the
substituted pathname string exceeded {PATH_MAX}.
ETXTBSY
The file to be renamed is 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 st_ctime field of renamed files and some do not. Applications
which make use of the st_ctime field 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() .
FUTURE DIRECTIONS
None.
SEE ALSO
link() , rmdir() , symlink() , unlink() , the Base Definitions volume of IEEE Std 1003.1-2001, <stdio.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 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 .