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RENAME(2)                     System Calls Manual                    RENAME(2)

NAME
     rename, renameat - change the name of a file

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <stdio.h>

     int
     rename(const char *from, const char *to);

     #include <unistd.h>

     int
     renameat(int fromfd, const char *from, int tofd, const char *to);

DESCRIPTION
     rename() causes the link named from to be renamed as to.  If to exists,
     it is first removed.  Both from and to must be of the same type (that is,
     both directories or both non-directories), and must reside on the same
     file system.

     rename() guarantees that an instance of to will always exist, even if the
     system should crash in the middle of the operation.

     If the final component of from is a symbolic link, the symbolic link is
     renamed, not the file or directory to which it points.

     If both from and to are pathnames of the same existing file in the file
     system's name space, rename() returns successfully and performs no other
     action.

     renameat() works the same way as rename() except if from (resp.  to) is
     relative.  In that case, it is looked up from a directory whose file
     descriptor was passed as fromfd (resp.  tofd).  Search permission is
     required on the directories named by fromfd and tofd.  fromfd or tofd can
     be set to AT_FDCWD in order to specify the current directory.

RETURN VALUES
     The rename() and renameat() functions return the value 0 if successful;
     otherwise the value -1 is returned and the global variable errno is set
     to indicate the error.

ERRORS
     rename() and renameat() will fail and neither of the argument files will
     be affected if:

     [EACCES]           A component of either path prefix denies search
                        permission, or the requested link requires writing in
                        a directory with a mode that denies write permission.

     [EBUSY]            from or to is the mount point for a mounted file
                        system.

     [EDQUOT]           The directory in which the entry for the new name is
                        being placed cannot be extended because the user's
                        quota of disk blocks on the file system containing the
                        directory has been exhausted.

     [EFAULT]           from or to points outside the process's allocated
                        address space.

     [EINVAL]           from is a parent directory of to, or an attempt is
                        made to rename `.' or `..'.

     [EIO]              An I/O error occurred while making or updating a
                        directory entry.

     [EISDIR]           to is a directory, but from is not a directory.

     [ELOOP]            Too many symbolic links were encountered in
                        translating either pathname.

     [ENAMETOOLONG]     A component of a pathname exceeded {NAME_MAX}
                        characters, or an entire path name exceeded {PATH_MAX}
                        characters.

     [ENOENT]           A component of the from path does not exist, or a path
                        prefix of to does not exist.

     [ENOSPC]           The directory in which the entry for the new name is
                        being placed cannot be extended because there is no
                        space left on the file system containing the
                        directory.

     [ENOTDIR]          A component of either path prefix is not a directory,
                        or from is a directory, but to is not a directory.

     [ENOTEMPTY]        to is a directory and is not empty.

     [EPERM]            The directory containing from is marked sticky, and
                        neither the containing directory nor from are owned by
                        the effective user ID.  Or the to file exists, the
                        directory containing to is marked sticky, and neither
                        the containing directory nor to are owned by the
                        effective user ID.

     [EROFS]            The requested link requires writing in a directory on
                        a read-only file system.

     [EXDEV]            The link named by to and the file named by from are on
                        different logical devices (file systems).  Note that
                        this error code will not be returned if the
                        implementation permits cross-device links.

     In addition, renameat() will fail if:

     [EBADF]            from or to does not specify an absolute path and
                        fromfd or tofd, respectively, is neither AT_FDCWD nor
                        a valid file descriptor open for reading or searching.

     [ENOTDIR]          from or to is not an absolute path and fromfd or tofd,
                        respectively, is a file descriptor associated with a
                        non-directory file.

SEE ALSO
     open(2), symlink(7)

STANDARDS
     The rename() function deviates from the semantics defined in IEEE Std
     1003.1-1990 ("POSIX.1"), which specifies that if both from and to link to
     the same existing file, rename() shall return successfully and performs
     no further action, whereas this implementation will remove the file
     specified by from unless both from and to are pathnames of the same file
     in the file system's name space.

     To retain conformance, a compatibility interface is provided by the POSIX
     Compatibility Library (libposix, -lposix) which is also be brought into
     scope if any of the _POSIX_SOURCE, _POSIX_C_SOURCE or _XOPEN_SOURCE
     preprocessor symbols are defined at compile-time: the rename() function
     conforms to IEEE Std 1003.1-1990 ("POSIX.1") and X/Open Portability Guide
     Issue 4, Version 2 ("XPG4.2").  renameat() conforms to IEEE Std
     1003.1-2008 ("POSIX.1").

BUGS
     The system can deadlock if a loop in the file system graph is present.
     This loop takes the form of an entry in directory `a', say `a/foo', being
     a hard link to directory `b', and an entry in directory `b', say `b/bar',
     being a hard link to directory `a'.  When such a loop exists and two
     separate processes attempt to perform `rename a/foo b/bar' and `rename
     b/bar a/foo', respectively, the system may deadlock attempting to lock
     both directories for modification.  Hard links to directories should be
     replaced by symbolic links by the system administrator.

NetBSD 10.99                     July 28, 2013                    NetBSD 10.99