Here's a yad program I put together to convert various file types to text using multiple command line tools.
Supported formats:
abw (need - abiword or unoconv)
dbk (need - abiword or unoconv)
doc (need - antiword, abiword, calligraconverter, catdoc, unoconv, or wvText)
docx (need - abiword, docx2txt, pandoc, unoconv, or unzip)
epub (need - abiword, ebook-convert, epub2txt, mutool, pandoc, or unoconv)
html (need - abiword, elinks, html2txt, links, links2, lynx, unoconv, or w3m)
kwd (need - abiword or unoconv)
odp (need - odt2txt)
odt (need - abiword, odt2txt, pandoc, or unoconv)
pdf (need - abiword, pdftotext, or unoconv)
rtf (need - abiword, pandoc, Ted, unrtf, or unoconv)
sxw (need - abiword, odt2txt, or unoconv)
xml (need - abiword, elinks, links, links2, lynx, or unoconv)
zabw (need - abiword or unoconv)
All conversions are done in the background (no gui is loaded for the various programs). You can set your preferences in the gui for which program to use for which file type.
There is also a symlink installed called "any2txt" that you can run from the command line (no gui) to do your conversion to text. The input file isn't deleted and the output file will be the same as the input file with the extension txt instead.