Recently on the Fediverse, Dave Fischer mentioned a neat hack:

In the decades-long process of getting my fvwm config JUST RIGHT, my xterm right-click menu now has a "duplicate" command, which opens a new xterm with the same geometry, on the same node, IN THE SAME DIRECTORY. (Directory info aquired via /proc.)

[...]

(See also a followup note.)

This led to @grawity sharing an xterm-native approach to this, using xterm's spawn-new-terminal() internal function that's available through xterm's keybindings facility.

I have a long-standing shell function in my shell that attempts to do this (imaginatively called 'spawn'), but this is only available in environments where my shell is set up, so I was quite interested in the whole area and did some experiments. The good news is that xterm's 'spawn-new-terminal' works, in that it will start a new xterm and the new xterm will be in the right directory. The bad news for me is that that's about all that it will do, and in my environment this has two limitations that will probably make it not something I use a lot.

The first limitation is that this starts an xterm that doesn't copy the command line state or settings of the parent xterm. If you've set special options on the parent xterm (for example, you like your root xterms to have a red foreground), this won't be carried over to the new xterm. Similarly, if you've increased (or decreased) the font size in your current xterm or otherwise changed its settings, spawn-new-terminal doesn't duplicate these; you get a default xterm. This is reasonable but disappointing.

(While spawn-new-terminal takes arguments that I believe it will pass to the new xterm, as far as I know there's no way to retrieve the current xterm's command line arguments to insert them here.)

The larger limitation for me is that when I'm at home, I'm often running SSH inside of an xterm in order to log in to some other system (I have a 'sshterm' script to automate all the aspects of this). What I really want when I 'duplicate' such an xterm is not a copy of the local xterm running a local shell (or even starting another SSH to the remove system), but the remote (shell) context, with the same (remote) current directory and so on. This is impossible to get in general and difficult to set up even for situations where it's theoretically possible. To use spawn-new-terminal effectively, you basically need either all local xterms or copious use of remote X forwarded over SSH (where the xterm is running on the remote system, so a duplicate of it will be as well and can get the right current directory).

Going through this experience has given me some ideas on how to improve the situation overall. Probably I should write a 'spawn' shell script to replace or augment my 'spawn' shell function so I can readily have it in more places. Then when I'm ssh'd in to a system, I can make the 'spawn' script at least print out a command line or two for me to copy and paste to get set up again.

(Two command lines is the easiest approach, with one command that starts the right xterm plus SSH combination and the other a 'cd' to the right place that I'd execute in the new logged in window. It's probably possible to combine these into an all-in-one script but that starts to get too clever in various ways, especially as SSH has no straightforward way to pass extra information to a login shell.)