Function 5Bh Create New File

mov dx, seg FileName

mov ds, dx

mov dx, offset FileName ;ds:dx points to new filename

mov cx, Attributes ;file attributes

mov ah, 5Bh ;Create New File

int 21h

jc error_handler ;carry set means error

mov Handle, ax ;handle of file

Create New File (Function 5Bh) creates a file and assigns it the first available handle. If the specified file already exists, this function fails.

Parameters

FileName

Points to a zero-terminated ASCII string that specifies the new filename. The name must be a valid MS-DOS filename and cannot contain wildcards.

Attributes

Specifies the attributes to assign to the new file. This parameter can be some combination of the following attributes:

Value

Meaning

ATTR_NORMAL (0000h)	File can be read from or written to.
ATTR_READONLY (0001h)	File can be read from but not written to.
ATTR_HIDDEN (0002h)	File does not appear in a directory listing.
ATTR_SYSTEM (0004h)	File is a system file.
ATTR_ARCHIVE (0020h)	File is marked for archiving.

Return Value

If the function is successful, the carry flag is clear and the AX register contains the new file handle. Otherwise, the carry flag is set and the AX register contains an error value, which may be one of the following:

Value

Name

0003h	ERROR_PATH_NOT_FOUND
0004h	ERROR_TOO_MANY_OPEN_FILES
0005h	ERROR_ACCESS_DENIED
0050h	ERROR_FILE_EXISTS

Comments

Create New File returns 0050h (ERROR_FILE_EXISTS) if a file with the specified name already exists.

When MS-DOS creates a file, it opens the file with read-and-write access and compatibility sharing mode and sets the file pointer to zero. If ATTR_READONLY is specified, the attribute takes effect only after the new file is closed.

If the specified file is on a network drive, the function creates the file only if network grants create access to the drive or directory.