PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

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

PROLOG         top

       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         top

       mkdir, mkdirat — make a directory relative to directory file
       descriptor

SYNOPSIS         top

       #include <sys/stat.h>

       int mkdir(const char *path, mode_t mode);
       int mkdirat(int fd, const char *path, mode_t mode);

DESCRIPTION         top

       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         top

       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         top

       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         top

   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         top

       None.

RATIONALE         top

       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         top

       None.

SEE ALSO         top

       chmod(3p), mkdtemp(3p), mknod(3p), umask(3p)

       The Base Definitions volume of POSIX.1‐2008, sys_stat.h(0p),
       sys_types.h(0p)

COPYRIGHT         top

       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)