rename - change the name of a file
Standard C Library (libc, -lc)
#include <stdio.h>
int
rename(const char *from, const char *to);
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.
A 0 value is returned if the operation succeeds, otherwise rename()
returns -1 and the global variable errno indicates the reason for the
failure.
rename() will fail and neither of the argument files will be affected if:
[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.
[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.
[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.
[ELOOP] Too many symbolic links were encountered in translating
either pathname.
[ENOTDIR] A component of either path prefix is not a directory,
or from is a directory, but to is not a directory.
[EISDIR] to is a directory, but from is not a directory.
[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.
[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.
[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.
[EIO] An I/O error occurred while making or updating a
directory entry.
[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.
[EINVAL] from is a parent directory of to, or an attempt is
made to rename `.' or `..'.
[ENOTEMPTY] to is a directory and is not empty.
open(2), symlink(7)
The rename() function deviates from the semantics defined in ISO/IEC
9945-1:1990 (``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 ISO/IEC 9945-1:1990 (``POSIX.1'') and X/Open Portability Guide
Issue 4.2 (``XPG4.2'').
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.
BSD June 4, 1993 BSD
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