.\" Copyright, the authors of the Linux man-pages project .\" .\" SPDX-License-Identifier: Linux-man-pages-copyleft .\" .TH unlink 2 (date) "Linux man-pages (unreleased)" .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 .P .BI "int unlink(const char *" path ); .P .BR "#include " "/* Definition of " AT_* " constants */" .B #include .P .BI "int unlinkat(int " dirfd ", const char *" path ", int " flags ); .fi .P .RS -4 Feature Test Macro Requirements for glibc (see .BR feature_test_macros (7)): .RE .P .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. .P 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. .P If the name referred to a symbolic link, the link is removed. .P 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. .P If .I path 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). .P If .I path is relative and .I dirfd is the special value .BR AT_FDCWD , then .I path is interpreted relative to the current working directory of the calling process (like .BR unlink () and .BR rmdir (2)). .P If .I path is absolute, then .I dirfd is ignored. .P .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 path . If the .B AT_REMOVEDIR flag is specified, it performs the equivalent of .BR rmdir (2) on .IR path . .P 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 path is not allowed for the process's effective UID, or one of the directories in .I path did not allow search permission. (See also .BR path_resolution (7).) .TP .B EBUSY .I path 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 path points outside your accessible address space. .TP .B EIO An I/O error occurred. .TP .B EISDIR .I path 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 path . .TP .B ENAMETOOLONG .I path was too long. .TP .B ENOENT A component in .I path does not exist or is a dangling symbolic link, or .I path is empty. .TP .B ENOMEM Insufficient kernel memory was available. .TP .B ENOTDIR A component used as a directory in .I path 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 path 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 FS_IOC_SETFLAGS (2const).) .TP .B EROFS .I path refers to a file on a read-only filesystem. .P 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 path 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 path refers to a directory, and .B AT_REMOVEDIR was not specified in .IR flags . .TP .B ENOTDIR .I path is relative and .I dirfd is a file descriptor referring to a file other than a directory. .SH STANDARDS POSIX.1-2024. .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 path is relative, 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)