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.\"     @(#)rename.2	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: release/9.1.0/lib/libc/sys/rename.2 184750 2008-11-07 15:01:40Z trasz $
.\"
.Dd April 10, 2008
.Dt RENAME 2
.Os
.Sh NAME
.Nm rename
.Nd change the name of a file
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdio.h
.Ft int
.Fn rename "const char *from" "const char *to"
.Ft int
.Fn renameat "int fromfd" "const char *from" "int tofd" "const char *to"
.Sh DESCRIPTION
The
.Fn rename
system call
causes the link named
.Fa from
to be renamed as
.Fa to .
If
.Fa to
exists, it is first removed.
Both
.Fa from
and
.Fa to
must be of the same type (that is, both directories or both
non-directories), and must reside on the same file system.
.Pp
The
.Fn rename
system call
guarantees that if
.Fa to
already exists, an instance of
.Fa to
will always exist, even if the system should crash in
the middle of the operation.
.Pp
If the final component of
.Fa from
is a symbolic link,
the symbolic link is renamed,
not the file or directory to which it points.
.Pp
The
.Fn renameat
system call is equivalent to
.Fn rename
except in the case where either
.Fa from
or
.Fa to
specifies a relative path.
If
.Fa from
is a relative path, the file to be renamed is located
relative to the directory associated with the file descriptor
.Fa fromfd
instead of the current working directory.
If the
.Fa to
is a relative path, the same happens only relative to the directory associated
with
.Fa tofd .
If the
.Fn renameat
is passed the special value
.Dv AT_FDCWD
in the
.Fa fromfd
or
.Fa tofd
parameter, the current working directory is used in the determination
of the file for the respective path parameter.
.\".Sh 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
.\".Pa a ,
.\"say
.\".Pa a/foo ,
.\"being a hard link to directory
.\".Pa b ,
.\"and an entry in
.\"directory
.\".Pa b ,
.\"say
.\".Pa b/bar ,
.\"being a hard link
.\"to directory
.\".Pa a .
.\"When such a loop exists and two separate processes attempt to
.\"perform
.\".Ql rename a/foo b/bar
.\"and
.\".Ql 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.
.Sh RETURN VALUES
.Rv -std rename
.Sh ERRORS
The
.Fn rename
system call
will fail and neither of the argument files will be
affected if:
.Bl -tag -width Er
.It Bq Er ENAMETOOLONG
A component of either pathname exceeded 255 characters,
or the entire length of either path name exceeded 1023 characters.
.It Bq Er ENOENT
A component of the
.Fa from
path does not exist,
or a path prefix of
.Fa to
does not exist.
.It Bq Er EACCES
A component of either path prefix denies search permission.
.It Bq Er EACCES
The requested link requires writing in a directory with a mode
that denies write permission.
.It Bq Er EACCES
The directory pointed at by the
.Fa from
argument denies write permission, and the operation would move
it to another parent directory.
.It Bq Er EPERM
The file pointed at by the
.Fa from
argument has its immutable, undeletable or append-only flag set, see the
.Xr chflags 2
manual page for more information.
.It Bq Er EPERM
The parent directory of the file pointed at by the
.Fa from
argument has its immutable or append-only flag set.
.It Bq Er EPERM
The parent directory of the file pointed at by the
.Fa to
argument has its immutable flag set.
.It Bq Er EPERM
The directory containing
.Fa from
is marked sticky,
and neither the containing directory nor
.Fa from
are owned by the effective user ID.
.It Bq Er EPERM
The file pointed at by the
.Fa to
argument
exists,
the directory containing
.Fa to
is marked sticky,
and neither the containing directory nor
.Fa to
are owned by the effective user ID.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating either pathname.
.It Bq Er ENOTDIR
A component of either path prefix is not a directory.
.It Bq Er ENOTDIR
The
.Fa from
argument
is a directory, but
.Fa to
is not a directory.
.It Bq Er EISDIR
The
.Fa to
argument
is a directory, but
.Fa from
is not a directory.
.It Bq Er EXDEV
The link named by
.Fa to
and the file named by
.Fa from
are on different logical devices (file systems).
Note that this error
code will not be returned if the implementation permits cross-device
links.
.It Bq Er 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.
.It Bq Er 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.
.It Bq Er EIO
An I/O error occurred while making or updating a directory entry.
.It Bq Er EROFS
The requested link requires writing in a directory on a read-only file
system.
.It Bq Er EFAULT
Path
points outside the process's allocated address space.
.It Bq Er EINVAL
The
.Fa from
argument
is a parent directory of
.Fa to ,
or an attempt is made to rename
.Ql .\&
or
.Ql \&.. .
.It Bq Er ENOTEMPTY
The
.Fa to
argument
is a directory and is not empty.
.El
.Pp
In addition to the errors returned by the
.Fn rename ,
the
.Fn renameat
may fail if:
.Bl -tag -width Er
.It Bq Er EBADF
The
.Fa from
argument does not specify an absolute path and the
.Fa fromfd
argument is neither
.Dv AT_FDCWD
nor a valid file descriptor open for searching, or the
.Fa to
argument does not specify an absolute path and the
.Fa tofd
argument is neither
.Dv AT_FDCWD
nor a valid file descriptor open for searching.
.It Bq Er ENOTDIR
The
.Fa from
argument is not an absolute path and
.Fa fromfd
is neither
.Dv AT_FDCWD
nor a file descriptor associated with a directory, or the
.Fa to
argument is not an absolute path and
.Fa tofd
is neither
.Dv AT_FDCWD
nor a file descriptor associated with a directory.
.El
.Sh SEE ALSO
.Xr chflags 2 ,
.Xr open 2 ,
.Xr symlink 7
.Sh STANDARDS
The
.Fn rename
system call is expected to conform to
.St -p1003.1-96 .
The
.Fn renameat
system call follows The Open Group Extended API Set 2 specification.
.Sh HISTORY
The
.Fn renameat
system call appeared in
.Fx 8.0 .