Getting contents of an attachment

[MatthewPearson]

I need to get the contents of an attachment and have tried using the following in a background script (for testing purposes only):

var sa = new GlideSysAttachment();
var binData = sa.getBytes('incident', '892a8ba0a400f000e9ece890a93b7172');
gs.print(binData);

However the response I get back is always something like:
[B@bdbc52
Which doesn't look at all like the file I have attached. I've tried a few different file attachment types and attached them to a few different types of record.
I have also tried passing a only GlideRecord on the sys_attachment table to getBytes and I get the same answer.
Once I have the contents of the file, I'd like to modify the content and create a new attachment (on a different record) with my modified content.
It looks like all of this should be possible, but I just can't get past the garbage I get out of getBytes.
I'm on Calgary Patch 2 Hotfix 5.

Thanks in advance

[Ben Collyer]

Glad you sorted it out. Although it is interesting you say GlideStringUtil didn't work for you.  Previously I have used this to retrieve attachments and base64 encode for building EML files:

var attBytes = (new GlideSysAttachment()).getBytes(grAttach);
var base64EncData = GlideStringUtil.base64Encode(attBytes);

Thanks for your solution @régissarlé