MKDIR(3P)

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 - make a directory

SYNOPSIS

#include <sys/stat.h>

int mkdir(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 st_atime, st_ctime, and st_mtime fields of the directory. Also, the st_ctime and st_mtime fields of the directory that contains the new entry shall be marked for update.

RETURN VALUE

Upon successful completion, mkdir() shall return 0. Otherwise, -1 shall be returned, no directory shall be created, and errno shall be set to indicate the error.

ERRORS

The mkdir() function 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 the path argument exceeds {PATH_MAX} or a pathname component 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 is not a directory.

EROFS
    The parent directory resides on a read-only file system.

The mkdir() function may fail if:

ELOOP
    More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the path argument.

ENAMETOOLONG
    As a result of encountering a symbolic link in resolution of the path argument, the length of the substituted pathname string exceeded {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.

FUTURE DIRECTIONS

None.

SEE ALSO

umask(), the Base Definitions volume of IEEE Std 1003.1-2001, <sys/stat.h>, <sys/types.h>

COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. 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.opengroup.org/unix/online.html .