1 .\" Hey Emacs! This file is -*- nroff -*- source.
3 .\" This manpage is Copyright (C) 1992 Drew Eckhardt;
4 .\" 1993 Michael Haardt
5 .\" 1993,1994 Ian Jackson.
6 .\" You may distribute it under the terms of the GNU General
7 .\" Public License. It comes with NO WARRANTY.
9 .\" Modified 1996-08-18 by urs
10 .\" Modified 2003-04-23 by Michael Kerrisk
11 .\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
13 .TH MKNOD 2 2010-09-20 "Linux" "Linux Programmer's Manual"
15 mknod \- create a special or ordinary file
18 .B #include <sys/types.h>
19 .B #include <sys/stat.h>
21 .B #include <unistd.h>
23 .BI "int mknod(const char *" pathname ", mode_t " mode ", dev_t " dev );
27 Feature Test Macro Requirements for glibc (see
28 .BR feature_test_macros (7)):
34 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
35 _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
41 creates a file system node (file, device special file or
44 with attributes specified by
51 argument specifies both the permissions to use and the type of node
53 It should be a combination (using bitwise OR) of one of the file types
54 listed below and the permissions for the new node.
56 The permissions are modified by the process's
58 in the usual way: the permissions of the created node are
59 .IR "(mode & ~umask)" .
61 The file type must be one of
68 .\" (S_IFSOCK since Linux 1.2.4)
69 to specify a regular file (which will be created empty), character
70 special file, block special file, FIFO (named pipe), or UNIX domain socket,
72 (Zero file type is equivalent to type
81 specifies the major and minor numbers of the newly created device
84 may be useful to build the value for
86 otherwise it is ignored.
90 already exists, or is a symbolic link, this call fails with an
94 The newly created node will be owned by the effective user ID of the
96 If the directory containing the node has the set-group-ID
97 bit set, or if the file system is mounted with BSD group semantics, the
98 new node will inherit the group ownership from its parent directory;
99 otherwise it will be owned by the effective group ID of the process.
102 returns zero on success, or \-1 if an error occurred (in which case,
104 is set appropriately).
108 The parent directory does not allow write permission to the process,
109 or one of the directories in the path prefix of
111 did not allow search permission.
113 .BR path_resolution (7).)
118 This includes the case where
120 is a symbolic link, dangling or not.
123 .IR pathname " points outside your accessible address space."
127 requested creation of something other than a regular file, device
128 special file, FIFO or socket.
131 Too many symbolic links were encountered in resolving
135 .IR pathname " was too long."
138 A directory component in
140 does not exist or is a dangling symbolic link.
143 Insufficient kernel memory was available.
146 The device containing
148 has no room for the new node.
151 A component used as a directory in
153 is not, in fact, a directory.
157 requested creation of something other than a regular file,
158 FIFO (named pipe), or UNIX domain socket, and the caller
159 is not privileged (Linux: does not have the
162 .\" For UNIX domain sockets and regular files, EPERM is only returned in
163 .\" Linux 2.2 and earlier; in Linux 2.4 and later, unprivileged can
164 .\" use mknod() to make these files.
165 also returned if the file system containing
167 does not support the type of node requested.
171 refers to a file on a read-only file system.
173 SVr4, 4.4BSD, POSIX.1-2001 (but see below).
174 .\" The Linux version differs from the SVr4 version in that it
175 .\" does not require root permission to create pipes, also in that no
176 .\" EMULTIHOP, ENOLINK, or EINTR error is documented.
178 POSIX.1-2001 says: "The only portable use of
180 is to create a FIFO-special file.
187 is not 0, the behavior of
190 However, nowadays one should never use
192 for this purpose; one should use
194 a function especially defined for this purpose.
196 Under Linux, this call cannot be used to create directories.
197 One should make directories with
199 .\" and one should make UNIX domain sockets with socket(2) and bind(2).
201 There are many infelicities in the protocol underlying NFS.
217 .BR path_resolution (7)