NAME
           rename - change the name of a file
SYNOPSIS
           rename(from, to)
           char *from, *to;
 
DESCRIPTION
           Rename causes the link named "from" to be renamed as "to". If to
           exists, then it is first removed.  Both from and to must be of the
           same type (i.e., 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.

CAVEAT
           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.  On systems
           with a symbolic link capability, hard links to directories should
           be replaced by symbolic links by the system administrator.

RETURN VALUE
           A 0 value is returned if the operation succeeds, otherwise rename
           returns -1 and the global variable errno indicates the reason for
           the failure.

ERRORS
           Rename will fail and nothing will change if any of the following
           are true:

           [ENOTDIR]
              A component of either path prefix is not a directory.

           [ENOENT]
              A component of either path prefix does not exist.

           [EACCES]
              A component of either path prefix denies search permission.

           [ENOENT]
              The file named by from does not exist.

           [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.

           [EACCES]
              The requested link requires writing in a directory with a mode
              that denies write permission.

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

           [EFAULT]
              Path points outside the process's allocated address space.
 
SEE ALSO
           open(2)