.\" This manpage is Copyright (C) 1992 Drew Eckhardt; .\" and Copyright (C) 1993 Michael Haardt; .\" and Copyright (C) 1993,1995 Ian Jackson .\" and Copyright (C) 2006, 2014 Michael Kerrisk .\" .\" %%%LICENSE_START(VERBATIM) .\" Permission is granted to make and distribute verbatim copies of this .\" manual provided the copyright notice and this permission notice are .\" preserved on all copies. .\" .\" Permission is granted to copy and distribute modified versions of this .\" manual under the conditions for verbatim copying, provided that the .\" entire resulting derived work is distributed under the terms of a .\" permission notice identical to this one. .\" .\" Since the Linux kernel and libraries are constantly changing, this .\" manual page may be incorrect or out-of-date. The author(s) assume no .\" responsibility for errors or omissions, or for damages resulting from .\" the use of the information contained herein. The author(s) may not .\" have taken the same level of care in the production of this manual, .\" which is licensed free of charge, as they might when working .\" professionally. .\" .\" Formatted or processed versions of this manual, if unaccompanied by .\" the source, must acknowledge the copyright and authors of this work. .\" %%%LICENSE_END .\" .\" Modified Sat Jul 24 00:35:52 1993 by Rik Faith .\" Modified Thu Jun 4 12:21:13 1998 by Andries Brouwer .\" Modified Thu Mar 3 09:49:35 2005 by Michael Haardt .\" 2007-03-25, mtk, added various text to DESCRIPTION. .\" .TH RENAME 2 2017-09-15 "Linux" "Linux Programmer's Manual" .SH NAME rename, renameat, renameat2 \- change the name or location of a file .SH SYNOPSIS .nf .B #include .PP .BI "int rename(const char *" oldpath ", const char *" newpath ); .BR "#include " "/* Definition of AT_* constants */" .B #include .PP .BI "int renameat(int " olddirfd ", const char *" oldpath , .BI " int " newdirfd ", const char *" newpath ); .PP .BI "int renameat2(int " olddirfd ", const char *" oldpath , .BI " int " newdirfd ", const char *" newpath \ ", unsigned int " flags ); .fi .PP .IR Note : There is no glibc wrapper for .BR renameat2 (); see NOTES. .PP .in -4n Feature Test Macro Requirements for glibc (see .BR feature_test_macros (7)): .in .PP .BR renameat (): .PD 0 .ad l .RS 4 .TP 4 Since glibc 2.10: _POSIX_C_SOURCE\ >=\ 200809L .TP Before glibc 2.10: _ATFILE_SOURCE .\" FIXME . need to define FTMs for renameat2(), once it hits glibc .RE .ad .PD .SH DESCRIPTION .BR rename () renames a file, moving it between directories if required. Any other hard links to the file (as created using .BR link (2)) are unaffected. Open file descriptors for .I oldpath are also unaffected. .PP Various restrictions determine whether or not the rename operation succeeds: see ERRORS below. .PP If .I newpath already exists, it will be atomically replaced, so that there is no point at which another process attempting to access .I newpath will find it missing. However, there will probably be a window in which both .I oldpath and .I newpath refer to the file being renamed. .PP If .I oldpath and .I newpath are existing hard links referring to the same file, then .BR rename () does nothing, and returns a success status. .PP If .I newpath exists but the operation fails for some reason, .BR rename () guarantees to leave an instance of .I newpath in place. .PP .I oldpath can specify a directory. In this case, .I newpath must either not exist, or it must specify an empty directory. .PP If .I oldpath refers to a symbolic link, the link is renamed; if .I newpath refers to a symbolic link, the link will be overwritten. .SS renameat() The .BR renameat () system call operates in exactly the same way as .BR rename (), except for the differences described here. .PP If the pathname given in .I oldpath is relative, then it is interpreted relative to the directory referred to by the file descriptor .I olddirfd (rather than relative to the current working directory of the calling process, as is done by .BR rename () for a relative pathname). .PP If .I oldpath is relative and .I olddirfd is the special value .BR AT_FDCWD , then .I oldpath is interpreted relative to the current working directory of the calling process (like .BR rename ()). .PP If .I oldpath is absolute, then .I olddirfd is ignored. .PP The interpretation of .I newpath is as for .IR oldpath , except that a relative pathname is interpreted relative to the directory referred to by the file descriptor .IR newdirfd . .PP See .BR openat (2) for an explanation of the need for .BR renameat (). .SS renameat2() .BR renameat2 () has an additional .I flags argument. A .BR renameat2 () call with a zero .I flags argument is equivalent to .BR renameat (). .PP The .I flags argument is a bit mask consisting of zero or more of the following flags: .TP .B RENAME_EXCHANGE Atomically exchange .IR oldpath and .IR newpath . Both pathnames must exist but may be of different types (e.g., one could be a non-empty directory and the other a symbolic link). .TP .B RENAME_NOREPLACE Don't overwrite .IR newpath of the rename. Return an error if .IR newpath already exists. .IP .B RENAME_NOREPLACE can't be employed together with .BR RENAME_EXCHANGE . .TP .BR RENAME_WHITEOUT " (since Linux 3.18)" .\" commit 0d7a855526dd672e114aff2ac22b60fc6f155b08 .\" commit 787fb6bc9682ec7c05fb5d9561b57100fbc1cc41 This operation makes sense only for overlay/union filesystem implementations. .IP Specifying .B RENAME_WHITEOUT creates a "whiteout" object at the source of the rename at the same time as performing the rename. The whole operation is atomic, so that if the rename succeeds then the whiteout will also have been created. .IP A "whiteout" is an object that has special meaning in union/overlay filesystem constructs. In these constructs, multiple layers exist and only the top one is ever modified. A whiteout on an upper layer will effectively hide a matching file in the lower layer, making it appear as if the file didn't exist. .IP When a file that exists on the lower layer is renamed, the file is first copied up (if not already on the upper layer) and then renamed on the upper, read-write layer. At the same time, the source file needs to be "whiteouted" (so that the version of the source file in the lower layer is rendered invisible). The whole operation needs to be done atomically. .IP When not part of a union/overlay, the whiteout appears as a character device with a {0,0} device number. .IP .B RENAME_WHITEOUT requires the same privileges as creating a device node (i.e., the .BR CAP_MKNOD capability). .IP .B RENAME_WHITEOUT can't be employed together with .BR RENAME_EXCHANGE . .IP .B RENAME_WHITEOUT requires support from the underlying filesystem. Among the filesystems that provide that support are shmem (since Linux 3.18), .\" shmem: commit 46fdb794e3f52ef18b859ebc92f0a9d7db21c5df ext4 (since Linux 3.18), .\" ext4: commit cd808deced431b66b5fa4e5c193cb7ec0059eaff and XFS (since Linux 4.1). .\" XFS: commit 7dcf5c3e4527cfa2807567b00387cf2ed5e07f00 .SH RETURN VALUE On success, zero is returned. On error, \-1 is returned, and .I errno is set appropriately. .SH ERRORS .TP .B EACCES Write permission is denied for the directory containing .I oldpath or .IR newpath , or, search permission is denied for one of the directories in the path prefix of .I oldpath or .IR newpath , or .I oldpath is a directory and does not allow write permission (needed to update the .I .. entry). (See also .BR path_resolution (7).) .TP .B EBUSY The rename fails because .IR oldpath " or " newpath is a directory that is in use by some process (perhaps as current working directory, or as root directory, or because it was open for reading) or is in use by the system (for example as mount point), while the system considers this an error. (Note that there is no requirement to return .B EBUSY in such cases\(emthere is nothing wrong with doing the rename anyway\(embut it is allowed to return .B EBUSY if the system cannot otherwise handle such situations.) .TP .B EDQUOT The user's quota of disk blocks on the filesystem has been exhausted. .TP .B EFAULT .IR oldpath " or " newpath " points outside your accessible address space." .TP .B EINVAL The new pathname contained a path prefix of the old, or, more generally, an attempt was made to make a directory a subdirectory of itself. .TP .B EISDIR .I newpath is an existing directory, but .I oldpath is not a directory. .TP .B ELOOP Too many symbolic links were encountered in resolving .IR oldpath " or " newpath . .TP .B EMLINK .I oldpath already has the maximum number of links to it, or it was a directory and the directory containing .I newpath has the maximum number of links. .TP .B ENAMETOOLONG .IR oldpath " or " newpath " was too long." .TP .B ENOENT The link named by .I oldpath does not exist; or, a directory component in .I newpath does not exist; or, .I oldpath or .I newpath is an empty string. .TP .B ENOMEM Insufficient kernel memory was available. .TP .B ENOSPC The device containing the file has no room for the new directory entry. .TP .B ENOTDIR A component used as a directory in .IR oldpath " or " newpath is not, in fact, a directory. Or, .I oldpath is a directory, and .I newpath exists but is not a directory. .TP .BR ENOTEMPTY " or " EEXIST .I newpath is a nonempty directory, that is, contains entries other than "." and "..". .TP .BR EPERM " or " EACCES The directory containing .I oldpath has the sticky bit .RB ( S_ISVTX ) set and the process's effective user ID is neither the user ID of the file to be deleted nor that of the directory containing it, and the process is not privileged (Linux: does not have the .B CAP_FOWNER capability); or .I newpath is an existing file and the directory containing it has the sticky bit set and the process's effective user ID is neither the user ID of the file to be replaced nor that of the directory containing it, and the process is not privileged (Linux: does not have the .B CAP_FOWNER capability); or the filesystem containing .I pathname does not support renaming of the type requested. .TP .B EROFS The file is on a read-only filesystem. .TP .B EXDEV .IR oldpath " and " newpath are not on the same mounted filesystem. (Linux permits a filesystem to be mounted at multiple points, but .BR rename () does not work across different mount points, even if the same filesystem is mounted on both.) .PP The following additional errors can occur for .BR renameat () and .BR renameat2 (): .TP .B EBADF .I olddirfd or .I newdirfd is not a valid file descriptor. .TP .B ENOTDIR .I oldpath is relative and .I olddirfd is a file descriptor referring to a file other than a directory; or similar for .I newpath and .I newdirfd .PP The following additional errors can occur for .BR renameat2 (): .TP .B EEXIST .I flags contains .B RENAME_NOREPLACE and .I newpath already exists. .TP .B EINVAL An invalid flag was specified in .IR flags . .TP .B EINVAL Both .B RENAME_NOREPLACE and .B RENAME_EXCHANGE were specified in .IR flags . .TP .B EINVAL Both .B RENAME_WHITEOUT and .B RENAME_EXCHANGE were specified in .IR flags . .TP .B EINVAL The filesystem does not support one of the flags in .IR flags . .TP .B ENOENT .I flags contains .B RENAME_EXCHANGE and .IR newpath does not exist. .TP .B EPERM .B RENAME_WHITEOUT was specified in .IR flags , but the caller does not have the .B CAP_MKNOD capability. .SH VERSIONS .BR renameat () was added to Linux in kernel 2.6.16; library support was added to glibc in version 2.4. .PP .BR renameat2 () was added to Linux in kernel 3.15. .\" FIXME . glibc support is pending. .SH CONFORMING TO .BR rename (): 4.3BSD, C89, C99, POSIX.1-2001, POSIX.1-2008. .PP .BR renameat (): POSIX.1-2008. .PP .BR renameat2 () is Linux-specific. .SH NOTES Glibc does not provide a wrapper for the .BR renameat2 () system call; call it using .BR syscall (2). .\" .SS Glibc notes On older kernels where .BR renameat () is unavailable, the glibc wrapper function falls back to the use of .BR rename (). When .I oldpath and .I newpath are relative pathnames, glibc constructs pathnames based on the symbolic links in .IR /proc/self/fd that correspond to the .I olddirfd and .IR newdirfd arguments. .SH BUGS On NFS filesystems, you can not assume that if the operation failed, the file was not renamed. If the server does the rename operation and then crashes, the retransmitted RPC which will be processed when the server is up again causes a failure. The application is expected to deal with this. See .BR link (2) for a similar problem. .SH SEE ALSO .BR mv (1), .BR chmod (2), .BR link (2), .BR symlink (2), .BR unlink (2), .BR path_resolution (7), .BR symlink (7) .SH COLOPHON This page is part of release 4.16 of the Linux .I man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at \%https://www.kernel.org/doc/man\-pages/.