MKDIR
Section: POSIX Programmer's Manual (3P)
Updated: 2013
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PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
NAME
mkdir, mkdirat
--- make a directory relative to directory file descriptor
SYNOPSIS
#include <sys/stat.h>
int mkdir(const char *path, mode_t mode);
int mkdirat(int fd, const char *path, mode_t mode);
DESCRIPTION
The
mkdir()
function shall create a new directory with name
path.
The file permission bits of the new directory shall be initialized from
mode.
These file permission bits of the
mode
argument shall be modified by the process' file creation mask.
When bits in
mode
other than the file permission bits are set, the meaning of these
additional bits is implementation-defined.
The directory's user ID shall be set to the process' effective user ID.
The directory's group ID shall be set to the group ID of the parent
directory or to the effective group ID of the process. Implementations
shall provide a way to initialize the directory's group ID to the group
ID of the parent directory. Implementations may, but need not, provide
an implementation-defined way to initialize the directory's group ID to
the effective group ID of the calling process.
The newly created directory shall be an empty directory.
If
path
names a symbolic link,
mkdir()
shall fail and set
errno
to
[EEXIST].
Upon successful completion,
mkdir()
shall mark for update the last data access, last data modification,
and last file status change timestamps of the directory. Also, the last
data modification and last file status change timestamps of the directory
that contains the new entry shall be marked for update.
The
mkdirat()
function shall be equivalent to the
mkdir()
function except in the case where
path
specifies a relative path. In this case the newly created directory is
created relative to the directory associated with the file descriptor
fd
instead of the current working directory. If the file descriptor was
opened without O_SEARCH, the function shall check whether directory
searches are permitted using the current permissions of the directory
underlying the file descriptor. If the file descriptor was opened with
O_SEARCH, the function shall not perform the check.
If
mkdirat()
is passed the special value AT_FDCWD in the
fd
parameter, the current working directory shall be used and the behavior
shall be identical to a call to
mkdir().
RETURN VALUE
Upon successful completion, these functions shall return 0.
Otherwise, these functions shall return -1 and set
errno
to indicate the error. If -1 is returned, no directory shall be created.
ERRORS
These functions shall fail if:
- EACCES
-
Search permission is denied on a component of the path prefix, or write
permission is denied on the parent directory of the directory to be
created.
- EEXIST
-
The named file exists.
- ELOOP
-
A loop exists in symbolic links encountered during resolution of the
path
argument.
- EMLINK
-
The link count of the parent directory would exceed
{LINK_MAX}.
- ENAMETOOLONG
-
The length of a component of a pathname is longer than
{NAME_MAX}.
- ENOENT
-
A component of the path prefix specified by
path
does not name an existing directory or
path
is an empty string.
- ENOSPC
-
The file system does not contain enough space to hold the contents of
the new directory or to extend the parent directory of the new
directory.
- ENOTDIR
-
A component of the path prefix names an existing file that is neither
a directory nor a symbolic link to a directory.
- EROFS
-
The parent directory resides on a read-only file system.
In addition, the
mkdirat()
function shall fail if:
- EBADF
-
The
path
argument does not specify an absolute path and the
fd
argument is neither AT_FDCWD nor a valid file descriptor open for reading
or searching.
- ENOTDIR
-
The
path
argument is not an absolute path and
fd
is a file descriptor associated with a non-directory file.
These functions may fail if:
- ELOOP
-
More than
{SYMLOOP_MAX}
symbolic links were encountered during resolution of the
path
argument.
- ENAMETOOLONG
-
The length of a pathname exceeds
{PATH_MAX},
or pathname resolution of a symbolic link produced an intermediate
result with a length that exceeds
{PATH_MAX}.
The following sections are informative.
EXAMPLES
Creating a Directory
The following example shows how to create a directory named
/home/cnd/mod1,
with read/write/search permissions for owner and group, and with
read/search permissions for others.
-
#include <sys/types.h>
#include <sys/stat.h>
int status;
...
status = mkdir("/home/cnd/mod1", S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);
APPLICATION USAGE
None.
RATIONALE
The
mkdir()
function originated in 4.2 BSD and was added to System V in Release 3.0.
4.3 BSD detects
[ENAMETOOLONG].
The POSIX.1-1990 standard required that the group ID of a newly created directory be
set to the group ID of its parent directory or to the effective group
ID of the creating process. FIPS 151-2 required that implementations provide
a way to have the group ID be set to the group ID of the containing
directory, but did not prohibit implementations also supporting a way
to set the group ID to the effective group ID of the creating process.
Conforming applications should not assume which group ID will be used. If
it matters, an application can use
chown()
to set the group ID after the directory is created, or determine under
what conditions the implementation will set the desired group ID.
The purpose of the
mkdirat()
function is to create a directory in directories other than the
current working directory without exposure to race conditions. Any part
of the path of a file could be changed in parallel to the call to
mkdir(),
resulting in unspecified behavior. By opening a file descriptor for
the target directory and using the
mkdirat()
function it can be guaranteed that the newly created directory is
located relative to the desired directory.
FUTURE DIRECTIONS
None.
SEE ALSO
chmod(),
mkdtemp(),
mknod(),
umask()
The Base Definitions volume of POSIX.1-2008,
<sys_stat.h>,
<sys_types.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.unix.org/online.html .
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
Index
- PROLOG
-
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- EXAMPLES
-
- Creating a Directory
-
- APPLICATION USAGE
-
- RATIONALE
-
- FUTURE DIRECTIONS
-
- SEE ALSO
-
- COPYRIGHT
-
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