This will thread an MH folder. It re-orders the messages (as sortm(1) would do), and annotates each one with a new header, "X-MH-Thread-Markup", which can be displayed by scan(1).
Together, this results in the messages being displayed in "threaded" order, as in trn(1) or mutt(1).
Sequences will be rewritten appropriately. The folder will also be "packed", as if 'folder -pack' had been run; see folder(1).
Here's some sample output from scan(1), after threading the folder:
430 03/23 mathew 3 [Asrg] Re: [OffTopic - NNTP] 431 03/23 Kee Hinckley 5 |- [Asrg] Re: [OffTopic - NNTP] 432 -03/23 Chuq Von Rospach 11 | |- Parameters for success? (was Re: [A 433 03/23 To:Chuq Von Rospa 4 | | \- Re: Parameters for success? (was 434 03/23 Matt Sergeant 3 | \- Re: [Asrg] Re: [OffTopic - NNTP] 435 03/23 Chuq Von Rospach 7 \- Re: [Asrg] Re: [OffTopic - NNTP]
The full manual page is available.
Download the tarball here: mhthread.tar.gz.
Download the script directly, as text: mhthread.txt.