1RENAME(2) Linux Programmer's Manual RENAME(2)
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6 rename, renameat, renameat2 - change the name or location of a file
7
9 #include <stdio.h>
10 int rename(const char *oldpath, const char *newpath);
12 #include <fcntl.h> /* Definition of AT_* constants */
14 #include <stdio.h>
15 int renameat(int olddirfd, const char *oldpath,
17 int newdirfd, const char *newpath);
18 int renameat2(int olddirfd, const char *oldpath,
20 int newdirfd, const char *newpath, unsigned int flags);
21 Note: There is no glibc wrapper for renameat2(); see NOTES.
23 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
25 renameat():
27 Since glibc 2.10:
28 _POSIX_C_SOURCE >= 200809L
29 Before glibc 2.10:
30 _ATFILE_SOURCE
31
33 rename() renames a file, moving it between directories if required.
34 Any other hard links to the file (as created using link(2)) are unaf‐
35 fected. Open file descriptors for oldpath are also unaffected.
36 Various restrictions determine whether or not the rename operation suc‐
38 ceeds: see ERRORS below.
39 If newpath already exists, it will be atomically replaced, so that
41 there is no point at which another process attempting to access newpath
42 will find it missing. However, there will probably be a window in
43 which both oldpath and newpath refer to the file being renamed.
44 If oldpath and newpath are existing hard links referring to the same
46 file, then rename() does nothing, and returns a success status.
47 If newpath exists but the operation fails for some reason, rename()
49 guarantees to leave an instance of newpath in place.
50 oldpath can specify a directory. In this case, newpath must either not
52 exist, or it must specify an empty directory.
53 If oldpath refers to a symbolic link, the link is renamed; if newpath
55 refers to a symbolic link, the link will be overwritten.
56 renameat()
58 The renameat() system call operates in exactly the same way as
59 rename(), except for the differences described here.
60 If the pathname given in oldpath is relative, then it is interpreted
62 relative to the directory referred to by the file descriptor olddirfd
63 (rather than relative to the current working directory of the calling
64 process, as is done by rename() for a relative pathname).
65 If oldpath is relative and olddirfd is the special value AT_FDCWD, then
67 oldpath is interpreted relative to the current working directory of the
68 calling process (like rename()).
69 If oldpath is absolute, then olddirfd is ignored.
71 The interpretation of newpath is as for oldpath, except that a relative
73 pathname is interpreted relative to the directory referred to by the
74 file descriptor newdirfd.
75 See openat(2) for an explanation of the need for renameat().
77 renameat2()
79 renameat2() has an additional flags argument. A renameat2() call with
80 a zero flags argument is equivalent to renameat().
81 The flags argument is a bit mask consisting of zero or more of the fol‐
83 lowing flags:
84 RENAME_EXCHANGE
86 Atomically exchange oldpath and newpath. Both pathnames must
87 exist but may be of different types (e.g., one could be a non-
88 empty directory and the other a symbolic link).
89 RENAME_NOREPLACE
91 Don't overwrite newpath of the rename. Return an error if new‐
92 path already exists.
93 RENAME_NOREPLACE can't be employed together with
95 RENAME_EXCHANGE.
96 RENAME_WHITEOUT (since Linux 3.18)
98 This operation makes sense only for overlay/union filesystem
99 implementations.
100 Specifying RENAME_WHITEOUT creates a "whiteout" object at the
102 source of the rename at the same time as performing the rename.
103 The whole operation is atomic, so that if the rename succeeds
104 then the whiteout will also have been created.
105 A "whiteout" is an object that has special meaning in
107 union/overlay filesystem constructs. In these constructs, mul‐
108 tiple layers exist and only the top one is ever modified. A
109 whiteout on an upper layer will effectively hide a matching file
110 in the lower layer, making it appear as if the file didn't
111 exist.
112 When a file that exists on the lower layer is renamed, the file
114 is first copied up (if not already on the upper layer) and then
115 renamed on the upper, read-write layer. At the same time, the
116 source file needs to be "whiteouted" (so that the version of the
117 source file in the lower layer is rendered invisible). The
118 whole operation needs to be done atomically.
119 When not part of a union/overlay, the whiteout appears as a
121 character device with a {0,0} device number.
122 RENAME_WHITEOUT requires the same privileges as creating a
124 device node (i.e., the CAP_MKNOD capability).
125 RENAME_WHITEOUT can't be employed together with RENAME_EXCHANGE.
127 RENAME_WHITEOUT requires support from the underlying filesystem.
129 Among the filesystems that provide that support are shmem (since
130 Linux 3.18), ext4 (since Linux 3.18), and XFS (since Linux 4.1).
131
133 On success, zero is returned. On error, -1 is returned, and errno is
134 set appropriately.
135
137 EACCES Write permission is denied for the directory containing oldpath
138 or newpath, or, search permission is denied for one of the
139 directories in the path prefix of oldpath or newpath, or oldpath
140 is a directory and does not allow write permission (needed to
141 update the .. entry). (See also path_resolution(7).)
142 EBUSY The rename fails because oldpath or newpath is a directory that
144 is in use by some process (perhaps as current working directory,
145 or as root directory, or because it was open for reading) or is
146 in use by the system (for example as mount point), while the
147 system considers this an error. (Note that there is no require‐
148 ment to return EBUSY in such cases—there is nothing wrong with
149 doing the rename anyway—but it is allowed to return EBUSY if the
150 system cannot otherwise handle such situations.)
151 EDQUOT The user's quota of disk blocks on the filesystem has been
153 exhausted.
154 EFAULT oldpath or newpath points outside your accessible address space.
156 EINVAL The new pathname contained a path prefix of the old, or, more
158 generally, an attempt was made to make a directory a subdirec‐
159 tory of itself.
160 EISDIR newpath is an existing directory, but oldpath is not a direc‐
162 tory.
163 ELOOP Too many symbolic links were encountered in resolving oldpath or
165 newpath.
166 EMLINK oldpath already has the maximum number of links to it, or it was
168 a directory and the directory containing newpath has the maximum
169 number of links.
170 ENAMETOOLONG
172 oldpath or newpath was too long.
173 ENOENT The link named by oldpath does not exist; or, a directory compo‐
175 nent in newpath does not exist; or, oldpath or newpath is an
176 empty string.
177 ENOMEM Insufficient kernel memory was available.
179 ENOSPC The device containing the file has no room for the new directory
181 entry.
182 ENOTDIR
184 A component used as a directory in oldpath or newpath is not, in
185 fact, a directory. Or, oldpath is a directory, and newpath
186 exists but is not a directory.
187 ENOTEMPTY or EEXIST
189 newpath is a nonempty directory, that is, contains entries other
190 than "." and "..".
191 EPERM or EACCES
193 The directory containing oldpath has the sticky bit (S_ISVTX)
194 set and the process's effective user ID is neither the user ID
195 of the file to be deleted nor that of the directory containing
196 it, and the process is not privileged (Linux: does not have the
197 CAP_FOWNER capability); or newpath is an existing file and the
198 directory containing it has the sticky bit set and the process's
199 effective user ID is neither the user ID of the file to be
200 replaced nor that of the directory containing it, and the
201 process is not privileged (Linux: does not have the CAP_FOWNER
202 capability); or the filesystem containing pathname does not sup‐
203 port renaming of the type requested.
204 EROFS The file is on a read-only filesystem.
206 EXDEV oldpath and newpath are not on the same mounted filesystem.
208 (Linux permits a filesystem to be mounted at multiple points,
209 but rename() does not work across different mount points, even
210 if the same filesystem is mounted on both.)
211 The following additional errors can occur for renameat() and
213 renameat2():
214 EBADF olddirfd or newdirfd is not a valid file descriptor.
216 ENOTDIR
218 oldpath is relative and olddirfd is a file descriptor referring
219 to a file other than a directory; or similar for newpath and
220 newdirfd
221 The following additional errors can occur for renameat2():
223 EEXIST flags contains RENAME_NOREPLACE and newpath already exists.
225 EINVAL An invalid flag was specified in flags.
227 EINVAL Both RENAME_NOREPLACE and RENAME_EXCHANGE were specified in
229 flags.
230 EINVAL Both RENAME_WHITEOUT and RENAME_EXCHANGE were specified in
232 flags.
233 EINVAL The filesystem does not support one of the flags in flags.
235 ENOENT flags contains RENAME_EXCHANGE and newpath does not exist.
237 EPERM RENAME_WHITEOUT was specified in flags, but the caller does not
239 have the CAP_MKNOD capability.
240
242 renameat() was added to Linux in kernel 2.6.16; library support was
243 added to glibc in version 2.4.
244 renameat2() was added to Linux in kernel 3.15.
246
248 rename(): 4.3BSD, C89, C99, POSIX.1-2001, POSIX.1-2008.
249 renameat(): POSIX.1-2008.
251 renameat2() is Linux-specific.
253
255 Glibc does not provide a wrapper for the renameat2() system call; call
256 it using syscall(2).
257 Glibc notes
259 On older kernels where renameat() is unavailable, the glibc wrapper
260 function falls back to the use of rename(). When oldpath and newpath
261 are relative pathnames, glibc constructs pathnames based on the sym‐
262 bolic links in /proc/self/fd that correspond to the olddirfd and
263 newdirfd arguments.
264
266 On NFS filesystems, you can not assume that if the operation failed,
267 the file was not renamed. If the server does the rename operation and
268 then crashes, the retransmitted RPC which will be processed when the
269 server is up again causes a failure. The application is expected to
270 deal with this. See link(2) for a similar problem.
271
273 mv(1), chmod(2), link(2), symlink(2), unlink(2), path_resolution(7),
274 symlink(7)
275
277 This page is part of release 4.16 of the Linux man-pages project. A
278 description of the project, information about reporting bugs, and the
279 latest version of this page, can be found at
280 https://www.kernel.org/doc/man-pages/.
281Linux 2017-09-15 RENAME(2)