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MKDIR(3P) POSIX Programmer's Manual MKDIR(3P)
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.
mkdir, mkdirat — make a directory relative to directory file
descriptor
#include <sys/stat.h>
int mkdir(const char *path, mode_t mode);
int mkdirat(int fd, const char *path, mode_t mode);
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().
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.
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.
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);
None.
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.
None.
chmod(3p), mkdtemp(3p), mknod(3p), umask(3p)
The Base Definitions volume of POSIX.1‐2008, sys_stat.h(0p),
sys_types.h(0p)
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 .
IEEE/The Open Group 2013 MKDIR(3P)
Pages that refer to this page: sys_stat.h(0p), mkdir(1p), pax(1p), chmod(3p), mkdtemp(3p), mknod(3p), rmdir(3p), umask(3p)