The PPVtxt program was originally developed for Post-Processing Verification of the text-only version of a book. PPVing requires a thorough inspection of a post-processor's HTML and text files. Many of the checks can be automated so the PPVer can concentrate on the more difficult details. The same checks a PPVer does at the start are valid for a post-processor at the end of that phase. Checks currently include: delimeter check, adjacent spaces check, orphan asterisk check, line length check, weird characters check, ligature check, training spaces check, ellipsis review, dash review, paragraph spacing check, italics check, double word check, common scanno check, initials review, chapter header review, and a group of smaller special checks.
PPtxt is the command-line version of this program. PPtxt can be downloaded from this link.
Simply run the program with the text file you want to check. It will generate a file pptxt.log with what it finds. It won't find everything, and it will complain about some things which are just fine. However it has proven over and over again that it can catch errors that the most careful post-processor can overlook.
PPVtxt has a user-friendly graphical user interface, but is currently not being maintained (is it available anywhere?).
See also PPhtml for a similar program that works on html files.
PPtxt and PPhtml are included in the latest versions of Guiguts and can be run from within it.
Note: There is also a newer version of pptxt, written in Python 3, which provides better support for UTF-8 text files. For more information, see the pptxt page.