I'm using GhostScript to merge to PDFs into one PDF. One of the PDFs has textbox fields (editable fields) that I created in Adobe Acrobat Pro 9. When I merge these two PDFs with GhostScript I lose the textbox fields.
Is there any way to merge these files (using GS or some other free linux software) that keeps the textbox fields intact?
Ghostscript is doing the equivalent of printing, so you will lose the editable fields.
I recommend pdftk. I'm not sure what you mean by "merge" but pdftk can concatenate multiple separate PDF files into a single PDF file, or it can use background/watermark to overlay one page on another.
see also http://stackoverflow.com/questions/434248/is-it-possible-to-programmatically-chain-several-pdf-files-preferably-from-com for other methods
Maybe you could give the exact commandline you're using to merge the two PDFs?
As for your "some other free linux software" part of your question: did you ever try pdftk (available on Linux and Windows)? It has a quite unusual way of constructing its commandline, but it works very well. See here for details: http://www.accesspdf.com/pdftk/ .