.\" $OpenBSD: mknod.2,v 1.20 2015/01/19 15:54:11 millert Exp $ .\" $NetBSD: mknod.2,v 1.6 1995/02/27 12:34:33 cgd Exp $ .\" .\" Copyright (c) 1980, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)mknod.2 8.1 (Berkeley) 6/4/93 .\" .Dd $Mdocdate: January 19 2015 $ .Dt MKNOD 2 .Os .Sh NAME .Nm mknod , .Nm mknodat .Nd make a special file node .Sh SYNOPSIS .Fd #include .Ft int .Fn mknod "const char *path" "mode_t mode" "dev_t dev" .Fd #include .Fd #include .Ft int .Fn mknodat "int fd" "const char *path" "mode_t mode" "dev_t dev" .Sh DESCRIPTION The .Fn mknod function creates .Fa path with a file type and mode of .Fa mode , as modified by .Xr umask 2 . Only FIFO and device special files are supported by this implementation. .Pp If .Fa mode is the bitwise OR of .Dv S_IFIFO and zero or more file permissions, and .Fa dev is zero, then a FIFO is created. If .Fa mode is the bitwise OR of .Dv S_IFCHR or .Dv S_IFBLK and zero or more file permissions, then a character or block device special (respectively) is created with major and minor device numbers extracted from .Fa dev . .Pp The .Fn mknodat function is equivalent to .Fn mknod except that where .Fa path specifies a relative path, the newly created device special file is created relative to the directory associated with file descriptor .Fa fd instead of the current working directory. .Pp If .Fn mknodat is passed the special value .Dv AT_FDCWD (defined in .In fcntl.h ) in the .Fa fd parameter, the current working directory is used and the behavior is identical to a call to .Fn mknod . .Pp Creating a device special file with .Fn mknod or .Fn mknodat requires superuser privileges. .Sh RETURN VALUES .Rv -std .Sh ERRORS .Fn mknod and .Fn mknodat will fail and the file will be not created if: .Bl -tag -width Er .It Bq Er EINVAL .Fa mode is an invalid file type or .Fa dev is an invalid value for that file type. .It Bq Er ENOTDIR A component of the path prefix is not a directory. .It Bq Er ENAMETOOLONG A component of a pathname exceeded .Dv NAME_MAX characters, or an entire pathname (including the terminating NUL) exceeded .Dv PATH_MAX bytes. .It Bq Er ENOENT A component of the path prefix does not exist. .It Bq Er EACCES Search permission is denied for a component of the path prefix. .It Bq Er ELOOP Too many symbolic links were encountered in translating the pathname. .It Bq Er EPERM .Fa mode is a device special and the process's effective user ID is not superuser. .It Bq Er EIO An I/O error occurred while making the directory entry or allocating the inode. .It Bq Er ENOSPC The directory in which the entry for the new node is being placed cannot be extended because there is no space left on the file system containing the directory. .It Bq Er ENOSPC There are no free inodes on the file system on which the node is being created. .It Bq Er EDQUOT The directory in which the entry for the new node is being placed cannot be extended because the user's quota of disk blocks on the file system containing the directory has been exhausted. .It Bq Er EDQUOT The user's quota of inodes on the file system on which the node is being created has been exhausted. .It Bq Er EROFS The named file resides on a read-only file system. .It Bq Er EEXIST The named file exists. .It Bq Er EFAULT .Fa path points outside the process's allocated address space. .It Bq Er EINVAL The process is running within an alternate root directory, as created by .Xr chroot 2 . .El .Pp Additionally, .Fn mknodat will fail if: .Bl -tag -width Er .It Bq Er EBADF The .Fa path argument specifies a relative path and the .Fa fd argument is neither .Dv AT_FDCWD nor a valid file descriptor. .It Bq Er ENOTDIR The .Fa path argument specifies a relative path and the .Fa fd argument is a valid file descriptor but it does not reference a directory. .It Bq Er EACCES The .Fa path argument specifies a relative path but search permission is denied for the directory which the .Fa fd file descriptor references. .El .Sh SEE ALSO .Xr chmod 2 , .Xr chroot 2 , .Xr mkfifo 2 , .Xr stat 2 , .Xr umask 2 .Sh STANDARDS The .Fn mknod and .Fn mknodat functions conform to .St -p1003.1-2008 . .Sh HISTORY The .Fn mknod system call first appeared in .At v4 , and .Fn mknodat has been available since .Ox 5.0 .