1MKDIR(3P)                  POSIX Programmer's Manual                 MKDIR(3P)
2
3
4

PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
10

NAME

12       mkdir, mkdirat — make a directory
13

SYNOPSIS

15       #include <sys/stat.h>
16
17       int mkdir(const char *path, mode_t mode);
18
19       #include <fcntl.h>
20
21       int mkdirat(int fd, const char *path, mode_t mode);
22

DESCRIPTION

24       The mkdir() function shall create a new directory with name path.   The
25       file  permission  bits  of  the new directory shall be initialized from
26       mode.  These file permission bits of the mode argument shall  be  modi‐
27       fied by the process' file creation mask.
28
29       When  bits  in  mode  other  than the file permission bits are set, the
30       meaning of these additional bits is implementation-defined.
31
32       The directory's user ID shall be set to the process' effective user ID.
33       The  directory's  group  ID  shall be set to the group ID of the parent
34       directory or to the effective group ID of the process.  Implementations
35       shall provide a way to initialize the directory's group ID to the group
36       ID of the parent directory. Implementations may, but need not,  provide
37       an implementation-defined way to initialize the directory's group ID to
38       the effective group ID of the calling process.
39
40       The newly created directory shall be an empty directory.
41
42       If path names a symbolic link, mkdir() shall  fail  and  set  errno  to
43       [EEXIST].
44
45       Upon successful completion, mkdir() shall mark for update the last data
46       access, last data modification, and last file status change  timestamps
47       of the directory. Also, the last data modification and last file status
48       change timestamps of the directory that contains the new entry shall be
49       marked for update.
50
51       The  mkdirat()  function  shall  be  equivalent to the mkdir() function
52       except in the case where path specifies a relative path. In  this  case
53       the  newly created directory is created relative to the directory asso‐
54       ciated with the file descriptor  fd  instead  of  the  current  working
55       directory.  If  the access mode of the open file description associated
56       with the file descriptor is not  O_SEARCH,  the  function  shall  check
57       whether  directory searches are permitted using the current permissions
58       of the directory underlying the file descriptor. If the access mode  is
59       O_SEARCH, the function shall not perform the check.
60
61       If  mkdirat() is passed the special value AT_FDCWD in the fd parameter,
62       the current working directory shall be used and the behavior  shall  be
63       identical to a call to mkdir().
64

RETURN VALUE

66       Upon successful completion, these functions shall return 0.  Otherwise,
67       these functions shall return -1 and set errno to indicate the error. If
68       -1 is returned, no directory shall be created.
69

ERRORS

71       These functions shall fail if:
72
73       EACCES Search  permission  is denied on a component of the path prefix,
74              or write permission is denied on the  parent  directory  of  the
75              directory to be created.
76
77       EEXIST The named file exists.
78
79       ELOOP  A loop exists in symbolic links encountered during resolution of
80              the path argument.
81
82       EMLINK The link count of the parent directory would exceed {LINK_MAX}.
83
84       ENAMETOOLONG
85              The  length  of  a  component  of  a  pathname  is  longer  than
86              {NAME_MAX}.
87
88       ENOENT A  component  of the path prefix specified by path does not name
89              an existing directory or path is an empty string.
90
91       ENOSPC The file system does not contain enough space to hold  the  con‐
92              tents  of the new directory or to extend the parent directory of
93              the new directory.
94
95       ENOTDIR
96              A component of the path prefix names an existing  file  that  is
97              neither a directory nor a symbolic link to a directory.
98
99       EROFS  The parent directory resides on a read-only file system.
100
101       In addition, the mkdirat() function shall fail if:
102
103       EACCES The  access mode of the open file description associated with fd
104              is not O_SEARCH and the permissions of the directory  underlying
105              fd do not permit directory searches.
106
107       EBADF  The  path  argument does not specify an absolute path and the fd
108              argument is neither AT_FDCWD nor a valid  file  descriptor  open
109              for reading or searching.
110
111       ENOTDIR
112              The  path  argument  is  not  an  absolute path and fd is a file
113              descriptor associated with a non-directory file.
114
115       These functions may fail if:
116
117       ELOOP  More than {SYMLOOP_MAX} symbolic links were  encountered  during
118              resolution of the path argument.
119
120       ENAMETOOLONG
121              The length of a pathname exceeds {PATH_MAX}, or pathname resolu‐
122              tion of a symbolic link produced an intermediate result  with  a
123              length that exceeds {PATH_MAX}.
124
125       The following sections are informative.
126

EXAMPLES

128   Creating a Directory
129       The   following   example   shows  how  to  create  a  directory  named
130       /home/cnd/mod1, with read/write/search permissions for owner and group,
131       and with read/search permissions for others.
132
133
134           #include <sys/types.h>
135           #include <sys/stat.h>
136
137           int status;
138           ...
139           status = mkdir("/home/cnd/mod1", S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);
140

APPLICATION USAGE

142       None.
143

RATIONALE

145       The mkdir() function originated in 4.2 BSD and was added to System V in
146       Release 3.0.
147
148       4.3 BSD detects [ENAMETOOLONG].
149
150       The POSIX.1‐1990 standard required that the group ID of a newly created
151       directory  be  set  to  the  group ID of its parent directory or to the
152       effective group ID of the creating process. FIPS  151‐2  required  that
153       implementations  provide a way to have the group ID be set to the group
154       ID of the containing directory, but did  not  prohibit  implementations
155       also  supporting a way to set the group ID to the effective group ID of
156       the creating process.  Conforming applications should not assume  which
157       group ID will be used. If it matters, an application can use chown() to
158       set the group ID after the directory is  created,  or  determine  under
159       what conditions the implementation will set the desired group ID.
160
161       The  purpose  of  the  mkdirat()  function  is to create a directory in
162       directories other than the current working directory  without  exposure
163       to  race conditions. Any part of the path of a file could be changed in
164       parallel to the call to mkdir(), resulting in unspecified behavior.  By
165       opening  a file descriptor for the target directory and using the mkdi‐
166       rat() function it can be guaranteed that the newly created directory is
167       located relative to the desired directory.
168

FUTURE DIRECTIONS

170       None.
171

SEE ALSO

173       chmod(), mkdtemp(), mknod(), umask()
174
175       The  Base  Definitions volume of POSIX.1‐2017, <fcntl.h>, <sys_stat.h>,
176       <sys_types.h>
177
179       Portions of this text are reprinted and reproduced in  electronic  form
180       from  IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
181       table Operating System Interface (POSIX), The Open Group Base  Specifi‐
182       cations  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of
183       Electrical and Electronics Engineers, Inc and The Open Group.   In  the
184       event of any discrepancy between this version and the original IEEE and
185       The Open Group Standard, the original IEEE and The Open Group  Standard
186       is  the  referee document. The original Standard can be obtained online
187       at http://www.opengroup.org/unix/online.html .
188
189       Any typographical or formatting errors that appear  in  this  page  are
190       most likely to have been introduced during the conversion of the source
191       files to man page format. To report such errors,  see  https://www.ker
192       nel.org/doc/man-pages/reporting_bugs.html .
193
194
195
196IEEE/The Open Group                  2017                            MKDIR(3P)
Impressum