RENAME(3)                  POSIX Programmer's Manual                 RENAME(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

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 aa 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(3)
