MKDIR(2)                    BSD System Calls Manual                   MKDIR(2)

NAME
     mkdir, mkdirat -- make a directory file

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 directory path is created with the access permissions specified by
     mode and restricted by the umask(2) of the calling process. See chmod(2)
     for the possible permission bit masks for mode.

     The directory's owner ID is set to the process's effective user ID.  The
     directory's group ID is set to that of the parent directory in which it
     is created.

     Note: the behavior of mkdir() is undefined when mode bits other than the
     low 9 bits are used. Use chmod(2) after mkdir() to explicitly set the
     other bits (See example below).

     The mkdirat() system call is equivalent to mkdir() 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 mkdirat() is
     passed the special value AT_FDCWD in the fd parameter, the current work-
     ing directory is used and the behavior is identical to a call to mkdir().

RETURN VALUES
     A 0 return value indicates success.  A -1 return value indicates an
     error, and an error code is stored in errno.

ERRORS
     mkdir() will fail and no directory will be created if:

     [EACCES]           Search permission is denied for a component of the
                        path prefix.

     [EACCES]           Write permission is denied for the parent directory.

     [EDQUOT]           The new directory cannot be created because the user's
                        quota of disk blocks on the file system that will con-
                        tain the directory has been exhausted.

     [EDQUOT]           The user's quota of inodes on the file system on which
                        the directory is being created has been exhausted.

     [EEXIST]           The named file exists.

     [EFAULT]           Path points outside the process's allocated address
                        space.

     [EIO]              An I/O error occurred while making the directory entry
                        or allocating the inode.

     [EIO]              An I/O error occurred while reading from or writing to
                        the file system.

     [EISDIR]           The named file is the root directory.

     [ELOOP]            Too many symbolic links were encountered in translat-
                        ing the pathname.  This is taken to be indicative of a
                        looping symbolic link.

     [EMLINK]           The parent directory already has {LINK_MAX} links.

     [ENAMETOOLONG]     A component of a pathname exceeded {NAME_MAX} charac-
                        ters, or an entire path name exceeded {PATH_MAX} char-
                        acters.

     [ENOENT]           A component of the path prefix does not exist or path
                        is an empty string.

     [ENOSPC]           The new directory cannot be created because there is
                        no space left on the file system that would contain
                        it.

     [ENOSPC]           There are no free inodes on the file system on which
                        the directory is being created.

     [ENOTDIR]          A component of the path prefix is not a directory.

     [EROFS]            The parent directory resides on a read-only file sys-
                        tem.

     In addition to the errors returned by the mkdir(), the mkdirat() function
     may 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 searching.

     [ENOTDIR]          The path argument is not an absolute path and fd is
                        neither AT_FDCWD nor a file descriptor associated with
                        a directory.

EXAMPLE
           int main (int argc, const char * argv[])
           {
                   /* The behavior of mkdir is undefined for anything other than the "permission" bits */
                   if (mkdir("/tmp/blah", 0777))
                           perror("/tmp/blah");

                   /* So we need to set the sticky/executable bits explicitly with chmod after calling mkdir */
                   if (chmod("/tmp/blah", 07777))
                           perror("/tmp/blah");
           }

LEGACY SYNOPSIS
     #include <sys/types.h>
     #include <sys/stat.h>

     The include file <sys/types.h> is necessary.

SEE ALSO
     chmod(2), stat(2), umask(2), compat(5)

STANDARDS
     The mkdir() function conforms to IEEE Std 1003.1-1988 (``POSIX.1'').  The
     mkdirat() system call is expected to conform to POSIX.1-2008 .

HISTORY
     The mkdirat() system call appeared in OS X 10.10

4.2 Berkeley Distribution      December 11, 1993     4.2 Berkeley Distribution