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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 .