.TH RENAME 2 "12 February 1983"
.UC 4
.SH NAME
rename \- change the name of a file
.SH SYNOPSIS
.ft B
.nf
rename(from, to)
char *from, *to;
.fi
.ft R
.SH DESCRIPTION
.I Rename
causes the link named
.I from
to be renamed as
.IR to .
If 
.I to
exists, then it is first removed.
Both 
.I from
and
.I to
must be of the same type (that is, both directories or both
non-directories), and must reside on the same file system.
.PP
.I Rename
guarantees that an instance of
.I to
will always exist, even if the system should crash in
the middle of the operation.
.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 \*(lqa\*(rq,
say \*(lqa/foo\*(rq,
being a hard link to directory \*(lqb\*(rq, and an entry in
directory \*(lqb\*(rq, say \*(lqb/bar\*(rq, being a hard link
to directory \*(lqa\*(rq.
When such a loop exists and two separate processes attempt to
perform \*(lqrename a/foo b/bar\*(rq and \*(lqrename b/bar a/foo\*(rq,
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 VALUE"
A 0 value is returned if the operation succeeds, otherwise
.I rename
returns \-1 and the global variable 
.I errno
indicates the reason for the failure.
.SH "ERRORS
.I Rename
will fail and neither of the argument files will be
affected if any of the following are true:
.TP 15
[ENOTDIR]
A component of either path prefix is not a directory.
.TP 15
[ENOENT]
A component of either path prefix does not exist.
.TP 15
[EACCES]
A component of either path prefix denies search permission.
.TP 15
[ENOENT]
The file named by \fIfrom\fP does not exist.
.TP 15
[EPERM]
The file named by \fIfrom\fP is a directory and the effective
user ID is not super-user.
.TP 15
[EXDEV]
The link named by \fIto\fP and the file named by \fIfrom\fP
are on different logical devices (file systems).  Note that this error
code will not be returned if the implementation permits cross-device
links.
.TP 15
[EACCES]
The requested link requires writing in a directory with a mode
that denies write permission.
.TP 15
[EROFS]
The requested link requires writing in a directory on a read-only file
system.
.TP 15
[EFAULT]
.I Path
points outside the process's allocated address space.
.TP 15
[EINVAL]
.I From
is a parent directory of
.IR to .
.SH "SEE ALSO"
open(2)