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 2008-12-01 "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)):
32 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500
36 creates a file system node (file, device special file or
39 with attributes specified by
46 argument specifies both the permissions to use and the type of node
48 It should be a combination (using bitwise OR) of one of the file types
49 listed below and the permissions for the new node.
51 The permissions are modified by the process's
53 in the usual way: the permissions of the created node are
54 .IR "(mode & ~umask)" .
56 The file type must be one of
63 .\" (S_IFSOCK since Linux 1.2.4)
64 to specify a regular file (which will be created empty), character
65 special file, block special file, FIFO (named pipe), or Unix domain socket,
67 (Zero file type is equivalent to type
76 specifies the major and minor numbers of the newly created device
79 may be useful to build the value for
81 otherwise it is ignored.
85 already exists, or is a symbolic link, this call fails with an
89 The newly created node will be owned by the effective user ID of the
91 If the directory containing the node has the set-group-ID
92 bit set, or if the file system is mounted with BSD group semantics, the
93 new node will inherit the group ownership from its parent directory;
94 otherwise it will be owned by the effective group ID of the process.
97 returns zero on success, or \-1 if an error occurred (in which case,
99 is set appropriately).
103 The parent directory does not allow write permission to the process,
104 or one of the directories in the path prefix of
106 did not allow search permission.
108 .BR path_resolution (7).)
113 This includes the case where
115 is a symbolic link, dangling or not.
118 .IR pathname " points outside your accessible address space."
122 requested creation of something other than a regular file, device
123 special file, FIFO or socket.
126 Too many symbolic links were encountered in resolving
130 .IR pathname " was too long."
133 A directory component in
135 does not exist or is a dangling symbolic link.
138 Insufficient kernel memory was available.
141 The device containing
143 has no room for the new node.
146 A component used as a directory in
148 is not, in fact, a directory.
152 requested creation of something other than a regular file,
153 FIFO (named pipe), or Unix domain socket, and the caller
154 is not privileged (Linux: does not have the
157 .\" For Unix domain sockets and regular files, EPERM is only returned in
158 .\" Linux 2.2 and earlier; in Linux 2.4 and later, unprivileged can
159 .\" use mknod() to make these files.
160 also returned if the file system containing
162 does not support the type of node requested.
166 refers to a file on a read-only file system.
168 SVr4, 4.4BSD, POSIX.1-2001 (but see below).
169 .\" The Linux version differs from the SVr4 version in that it
170 .\" does not require root permission to create pipes, also in that no
171 .\" EMULTIHOP, ENOLINK, or EINTR error is documented.
173 POSIX.1-2001 says: "The only portable use of
175 is to create a FIFO-special file.
182 is not 0, the behavior of
185 However, nowadays one should never use
187 for this purpose; one should use
189 a function especially defined for this purpose.
191 Under Linux, this call cannot be used to create directories.
192 One should make directories with
194 .\" and one should make Unix domain sockets with socket(2) and bind(2).
196 There are many infelicities in the protocol underlying NFS.
212 .BR path_resolution (7)