Hey, Scripting Guy! How can I add a line to the top of a text file?

— FT

Hey, FT. You know, at one point in his career Sir Arthur Conan Doyle actually killed off Sherlock Holmes, figuring he’d written everything anyone could ever write about the master detective. Public outcry soon made him change his mind, and in short order he brought Sherlock Holmes back to life. (Creating, along the way, the basic plotline for every soap opera ever written.)

We Scripting Guys can empathize with Sir Arthur Conan Doyle. After all, we periodically think, “Well, that’s it; we’ve finally written everything anyone could ever write about text files.” No sooner do we think that than we seem to get a flurry of questions about text files, including three people who asked this same thing: how can I add a line to the top of a text file?

Elementary, my dear Watson (uh, my dear FT). All you have to do is use a script similar to this:

Const ForReading = 1
Const ForWriting = 2

Set objFSO = CreateObject(“Scripting.FileSystemObject”)
Set objFile = objFSO.OpenTextFile(“C:\Scripts\Test.txt”, ForReading)
strContents = objFile.ReadAll
objFile.Close
strFirstLine = “This is the new first line in the text file.”
strNewContents = strFirstLine & vbCrLf & strContents
Set objFile = objFSO.OpenTextFile(“C:\Scripts\Test.txt”, ForWriting)
objFile.WriteLine strNewContents
objFile.Close

Ah, yes, now the game is afoot, isn’t it? We begin by creating a pair of constants – ForReading and ForWriting – that we’ll use when working with our text file. We create an instance of the FileSystemObject and then use the OpenTextFile method to open the file C:\Scripts\Test.txt for reading:

Set objFile = objFSO.OpenTextFile(“C:\Scripts\Test.txt”, ForReading)

Now that the file is open we use the ReadAll method to read the entire contents of the file and store those contents in a variable named strContents. We then immediately close the file Test.txt. Why? Well, the FileSystemObject allows you to open a file for reading or for writing, but you can’t do both at the same time. To add a new line to the top of the file, we’re going to have to write to the file; that means we’ll have to reopen it, but for writing.

Next we need to construct the new contents for the file. We can’t directly add a line to the top of the text file; the FileSystemObject only allows you to add new lines to the end of a text file. Therefore, what we’ll have to do is create an entirely new file in memory and then replace the existing contents of Test.txt with this new file. Our new file will consist of three parts: a new first line; a carriage return-linefeed; and the existing contents of the file. To construct this file we start off by using this code to store the new first line in a variable named strFirstLine:

strFirstLine = “This is the new first line in the text file.”

We then use this line of code to concatenate the new first line, a carriage return-linefeed (using the VBScript constant vbCrLf) and the existing contents of the file (which we stored in the variable strContents):

strNewContents = strFirstLine & vbCrLf & strContents

All that’s left now is to reopen Test.txt (for writing this time), then use the WriteLine method to replace the exiting contents with our new file:

Set objFile = objFSO.OpenTextFile(“C:\Scripts\Test.txt”, ForWriting)
objFile.WriteLine strNewContents

We then call the Close method and, just like that, case closed. Well, OK, file closed. Hey, we’re just trying to do what Sherlock Holmes would do.

Speaking of which, did you know that Sherlock Holmes had an older brother named Mycroft? It’s true. Supposedly Mycroft had a lot of potential, but was too lazy to really do anything interesting or useful.

Hey, what do you mean that sounds familiar? Never mind; you’re probably thinking about some other daily scripting columnist.