Inside Macintosh: AppleScript Scripting Additions Guide /

Chapter 2 - Scripting Addition Commands / Command Definitions

/

Write

The Write command writes data to a specified file, beginning at the file mark. It is one of several commands provided by the Read/Write Commands scripting addition. For more information about these commands, see "Using Read/Write Commands,".

SYNTAX

write dataToWrite to referenceToFile 
   [ for bytesToWrite ] ¬
    [ starting at startingByte ] 

PARAMETERS

dataToWrite

The data to be written. The format of the data should match the file type.
Class: (varies among applications)

referenceToFile

A reference of the form file nameString or alias nameString, or a file reference number previously obtained with the Open for Access command (see "Notes").
Class: Reference or integer

bytesToWrite

The number of bytes to write. The Write command returns an error if you pass a negative number in this parameter.
Class: Integer

startingByte

Specifies the offset of the byte at which to begin writing. A positive integer indicates the offset from the beginning of the file, and a negative integer indicates the offset from the end of the file.
Class: Integer

RESULT

None

EXAMPLES

This example writes "abcde" to the file MyFile.

write "abcde" to file "Hard Disk:MyFile"

The next example returns an error because fewer bytes are specified for the dataToWrite parameter than are specified for the for bytesToWrite parameter:

write "abcde" to file "Hard Disk:MyFile" for 8 

If the data to write is longer than the bytes specified by the bytesToWrite parameter, the Write command truncates the data. For example, this Write command writes the number 5 to the file MyFile as a short integer (2 bytes) rather than an integer (4 bytes):

write 5 to file "Hard Disk:MyFile" for 2

The next example specifies a negative value for the startingByte parameter. It writes the number 5 as a short integer starting at the 8th byte before the end of the file.

write 5 to file "Hard Disk:MyFile" starting at -8 for 2

NOTES

The file mark is a marker used by the File Manager that indicates the byte at which the Read command expects to begin reading data. By default, the file mark is the first byte of the file. The Write command begins writing at the current file mark and sets the file mark to the byte after the last byte written. The Read command can also reset the file mark.

To set the file mark without reading or writing data, write a string of zero length to the byte to which you want to set the mark. For example, this script sets the file mark for the file specified by fileRefNum to the fourth byte in
the file:

write "" to fileRefNum starting at 4  

To specify the name (nameString) of a file, use a string of the form "Disk:Folder1:
Folder2:...:Filename" as described in Chapter 5, "Objects and References,"
of the AppleScript Language Guide. If you specify only the name of the file (Filename) instead of its entire pathname, AppleScript attempts to find the file in the current directory

The Write command attempts to match a reference to a file or an alias with a file previously opened with the Open for Access command. If a match is found, it simply writes the specified data. If no match is found but the file can be located on disk, the Write command opens the file, writes the specified data, then closes the file. The file mark for a file opened in this fashion is always
at the beginning of the file. If the file cannot be found at all, the Write command returns an error.

If you specify a file reference number previously obtained with the Open for Access command, the Write command writes the specified data immediately.

ERRORS

Error number	Error message
-34	Disk <name> is full.
-38	File <name> wasn't open.
-44	Disk <name> is write protected.
-45	File <name> is locked.
-49	File <name> is already open.
-50	Parameter error.
-51	File reference number error.
-61	File not open with write permission.
-108	Out of memory.