# How can I get all the defined lengths in a document?

I would like to have a big list with all the lengths that have been defined in my document, along with their values. (Specifically, I'm making a baposter poster and I want to remove the header and replace it with my own inside a headerbox, but the question is more general.) How can I get LaTeX to print all 'em lengths out, either to the log file or on the page?

latex has no information about the names given to length registers. It could print out the current values of allocated length registers as dimen0.... dimen...300 or however many have been allocated but can not know of declared names like \footskip etc.
• @E.P. they live in tex's hash table of defined names but similarly you can not find all the names defined with \newcommand or \def This is quite common, if you write a program in most programming languages, you can not find, from within the program itself, the names of all defined variables. – David Carlisle Sep 20 '17 at 14:51
• It doesn't appear to get on very well with the baposter class, though. – E.P. Sep 20 '17 at 14:19
• too bad for the baposter class and its users... I am not sure if other package layouts will help either. – user4686 Sep 20 '17 at 14:24