.\" This manpage is Copyright (C) 1992 Drew Eckhardt; .\" and Copyright (C) 1993 Ian Jackson .\" and Copyright (C) 2006, 2014 Michael Kerrisk. .\" .\" SPDX-License-Identifier: Linux-man-pages-copyleft .\" .\" 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 2023-03-30 "Linux man-pages 6.05.01" .SH NAME unlink, unlinkat \- delete a name and possibly the file it refers to .SH LIBRARY Standard C library .RI ( libc ", " \-lc ) .SH SYNOPSIS .nf .B #include .PP .BI "int unlink(const char *" pathname ); .PP .BR "#include " "/* Definition of " AT_* " constants */" .B #include .PP .BI "int unlinkat(int " dirfd ", const char *" pathname ", int " flags ); .fi .PP .RS -4 Feature Test Macro Requirements for glibc (see .BR feature_test_macros (7)): .RE .PP .BR unlinkat (): .nf Since glibc 2.10: _POSIX_C_SOURCE >= 200809L Before glibc 2.10: _ATFILE_SOURCE .fi .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 to indicate the error. .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 .B 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 since Linux 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 pathname is relative but .I dirfd is neither .B AT_FDCWD nor 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 STANDARDS POSIX.1-2008. .SH HISTORY .TP .BR unlink () SVr4, 4.3BSD, POSIX.1-2001. .\" SVr4 documents additional error .\" conditions EINTR, EMULTIHOP, ETXTBSY, ENOLINK. .TP .BR unlinkat () POSIX.1-2008. Linux 2.6.16, glibc 2.4. .SS glibc 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 .I /proc/self/fd that corresponds to the .I 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)