.\" This manpage is Copyright (C) 1992 Drew Eckhardt; .\" and Copyright (C) 1993 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 .\" .\" Since the Linux kernel and libraries are constantly changing, this .\" manual page may be incorrect or out-of-date.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 1993-07-24 by Rik Faith .\" Modified 1996-09-08 by Arnt Gulbrandsen .\" Modified 1997-01-31 by Eric S. Raymond .\" Modified 2001-05-17 by aeb .\" Modified 2004-06-23 by Michael Kerrisk .\" .TH UNLINK 2 2017-09-15 "Linux" "Linux Programmer's Manual" .SH NAME unlink, unlinkat \- delete a name and possibly the file it refers to .SH SYNOPSIS .nf .B #include .PP .BI "int unlink(const char *" pathname ); .BR "#include " "/* Definition of AT_* constants */" .B #include .PP .BI "int unlinkat(int " dirfd ", const char *" pathname ", int " flags ); .fi .PP .in -4n Feature Test Macro Requirements for glibc (see .BR feature_test_macros (7)): .in .PP .BR unlinkat (): .PD 0 .ad l .RS 4 .TP 4 Since glibc 2.10: _POSIX_C_SOURCE\ >=\ 200809L .TP Before glibc 2.10: _ATFILE_SOURCE .RE .ad .PD .SH DESCRIPTION .BR unlink () deletes a name from the filesystem. If that name was the last link to a file and no processes have the file open, the file is deleted and the space it was using is made available for reuse. .PP If the name was the last link to a file but any processes still have the file open, the file will remain in existence until the last file descriptor referring to it is closed. .PP If the name referred to a symbolic link, the link is removed. .PP If the name referred to a socket, FIFO, or device, the name for it is removed but processes which have the object open may continue to use it. .SS unlinkat() The .BR unlinkat () system call operates in exactly the same way as either .BR unlink () or .BR rmdir (2) (depending on whether or not .I flags includes the .B AT_REMOVEDIR flag) except for the differences described here. .PP If the pathname given in .I pathname is relative, then it is interpreted relative to the directory referred to by the file descriptor .I dirfd (rather than relative to the current working directory of the calling process, as is done by .BR unlink () and .BR rmdir (2) for a relative pathname). .PP If the pathname given in .I pathname is relative and .I dirfd is the special value .BR AT_FDCWD , then .I pathname is interpreted relative to the current working directory of the calling process (like .BR unlink () and .BR rmdir (2)). .PP If the pathname given in .I pathname is absolute, then .I dirfd is ignored. .PP .I flags is a bit mask that can either be specified as 0, or by ORing together flag values that control the operation of .BR unlinkat (). Currently, only one such flag is defined: .TP .B AT_REMOVEDIR By default, .BR unlinkat () performs the equivalent of .BR unlink () on .IR pathname . If the .B AT_REMOVEDIR flag is specified, then performs the equivalent of .BR rmdir (2) on .IR pathname . .PP See .BR openat (2) for an explanation of the need for .BR unlinkat (). .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 access to the directory containing .I pathname is not allowed for the process's effective UID, or one of the directories in .I pathname did not allow search permission. (See also .BR path_resolution (7).) .TP .BR EBUSY The file .I pathname cannot be unlinked because it is being used by the system or another process; for example, it is a mount point or the NFS client software created it to represent an active but otherwise nameless inode ("NFS silly renamed"). .TP .B EFAULT .I pathname points outside your accessible address space. .TP .B EIO An I/O error occurred. .TP .B EISDIR .I pathname refers to a directory. (This is the non-POSIX value returned by Linux since 2.1.132.) .TP .B ELOOP Too many symbolic links were encountered in translating .IR pathname . .TP .B ENAMETOOLONG .IR pathname " was too long." .TP .B ENOENT A component in .I pathname does not exist or is a dangling symbolic link, or .I pathname is empty. .TP .B ENOMEM Insufficient kernel memory was available. .TP .B ENOTDIR A component used as a directory in .I pathname is not, in fact, a directory. .TP .B EPERM The system does not allow unlinking of directories, or unlinking of directories requires privileges that the calling process doesn't have. (This is the POSIX prescribed error return; as noted above, Linux returns .B EISDIR for this case.) .TP .BR EPERM " (Linux only)" The filesystem does not allow unlinking of files. .TP .BR EPERM " or " EACCES The directory containing .I pathname has the sticky bit .RB ( S_ISVTX ) set and the process's effective UID is neither the UID 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). .TP .B EPERM The file to be unlinked is marked immutable or append-only. (See .BR ioctl_iflags (2).) .TP .B EROFS .I pathname refers to a file on a read-only filesystem. .PP The same errors that occur for .BR unlink () and .BR rmdir (2) can also occur for .BR unlinkat (). The following additional errors can occur for .BR unlinkat (): .TP .B EBADF .I dirfd is not a valid file descriptor. .TP .B EINVAL An invalid flag value was specified in .IR flags . .TP .B EISDIR .I pathname refers to a directory, and .B AT_REMOVEDIR was not specified in .IR flags . .TP .B ENOTDIR .I pathname is relative and .I dirfd is a file descriptor referring to a file other than a directory. .SH VERSIONS .BR unlinkat () was added to Linux in kernel 2.6.16; library support was added to glibc in version 2.4. .SH CONFORMING TO .BR unlink (): SVr4, 4.3BSD, POSIX.1-2001, POSIX.1-2008. .\" SVr4 documents additional error .\" conditions EINTR, EMULTIHOP, ETXTBSY, ENOLINK. .PP .BR unlinkat (): POSIX.1-2008. .SH NOTES .SS Glibc notes On older kernels where .BR unlinkat () is unavailable, the glibc wrapper function falls back to the use of .BR unlink () or .BR rmdir (2). When .I pathname is a relative pathname, glibc constructs a pathname based on the symbolic link in .IR /proc/self/fd that corresponds to the .IR dirfd argument. .SH BUGS Infelicities in the protocol underlying NFS can cause the unexpected disappearance of files which are still being used. .SH SEE ALSO .BR rm (1), .BR unlink (1), .BR chmod (2), .BR link (2), .BR mknod (2), .BR open (2), .BR rename (2), .BR rmdir (2), .BR mkfifo (3), .BR remove (3), .BR path_resolution (7), .BR symlink (7) .SH COLOPHON This page is part of release 5.04 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/.