-.\" Hey Emacs! This file is -*- nroff -*- source.
-.\"
.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
-.\" 1993 Ian Jackson.
+.\" 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.
.\"
.\" 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 <faith@cs.unc.edu>
.\" Modified 1996-09-08 by Arnt Gulbrandsen <agulbra@troll.no>
.\" Modified 2001-05-17 by aeb
.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
.\"
-.TH UNLINK 2 2004-06-23 "Linux" "Linux Programmer's Manual"
+.TH UNLINK 2 2014-08-19 "Linux" "Linux Programmer's Manual"
.SH NAME
-unlink \- delete a name and possibly the file it refers to
+unlink, unlinkat \- delete a name and possibly the file it refers to
.SH SYNOPSIS
+.nf
.B #include <unistd.h>
.sp
.BI "int unlink(const char *" pathname );
+.sp
+.BR "#include <fcntl.h> " "/* Definition of AT_* constants */"
+.B #include <unistd.h>
+.sp
+.BI "int unlinkat(int " dirfd ", const char *" pathname ", int " flags );
+.fi
+.sp
+.in -4n
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.in
+.sp
+.BR unlinkat ():
+.PD 0
+.ad l
+.RS 4
+.TP 4
+Since glibc 2.10:
+_XOPEN_SOURCE\ >=\ 700 || _POSIX_C_SOURCE\ >=\ 200809L
+.TP
+Before glibc 2.10:
+_ATFILE_SOURCE
+.RE
+.ad
+.PD
.SH DESCRIPTION
.BR unlink ()
-deletes a name from the file system.
+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
+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.
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
+the file open, the file will remain in existence until the last file
descriptor referring to it is closed.
-If the name referred to a symbolic link the link is removed.
+If the name referred to a symbolic link, the link is removed.
-If the name referred to a socket, fifo or device the name for it is
+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.
-.SH "RETURN VALUE"
+.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.
+
+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).
+
+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)).
+
+If the pathname given in
+.I pathname
+is absolute, then
+.I dirfd
+is ignored.
+
+.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
(See also
.BR path_resolution (7).)
.TP
-.BR EBUSY " (not on Linux)"
+.BR EBUSY
The file
.I pathname
cannot be unlinked because it is being used by the system
-or another process and the implementation considers this an error.
+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
for this case.)
.TP
.BR EPERM " (Linux only)"
-The file system does not allow unlinking of files.
+The filesystem does not allow unlinking of files.
.TP
.BR EPERM " or " EACCES
The directory containing
.TP
.B EROFS
.I pathname
-refers to a file on a read-only file system.
-.SH "CONFORMING TO"
-SVr4, 4.3BSD, POSIX.1-2001.
+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.
+
+.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 (2)
+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"
+.SH SEE ALSO
.BR rm (1),
.BR chmod (2),
.BR link (2),
.BR open (2),
.BR rename (2),
.BR rmdir (2),
-.BR unlinkat (2),
.BR mkfifo (3),
.BR remove (3),
.BR path_resolution (7),
.BR symlink (7)
+.SH COLOPHON
+This page is part of release 3.79 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
+\%http://www.kernel.org/doc/man\-pages/.
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