Matthew Saroff asked,
| I have my .procmailrc setup to forwward email to another (email
| only) account. When I am not going to be at the account, I turn
| forwarding off.
| What I'd like to be able to do is to change this state from my
| (email only) account.
| I realize that this gets into a nasty kettle of fish with a
| program modifying itself. I do this on my shell without a problem.
As Timothy Luoma has posted, a self-modifying .procmailrc is not needed.
Timothy's post gives the usual method: recipes that, upon receipt of trigger
letters from your other account, touch or rm a signal file.
If you can determine in advance what times the forwarding should start and
stop, you can also write a recipe based on checking the timestamp and date
in the From_ line; the regexp can get complicated but the method works very
reliably for me.