mkdir

MKDIR(3POSIX)               POSIX Programmer's Manual              MKDIR(3POSIX)



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 .



IEEE/The Open Group                   2013                         MKDIR(3POSIX)