int mkdir(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 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.
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.
The mkdir() function shall fail if:
The mkdir() function may fail if:
The following sections are informative.
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);
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.
umask() , the Base Definitions volume of IEEE Std 1003.1-2001, <sys/stat.h>, <sys/types.h>