[gglitch]

Similar. I've ended up at these functions in .bashrc:

   # Append a timestamped entry to the journal
   log() {
       printf "$(date +%Y-%m-%d--%H:%M)   %s\n" "$*" >> $journal
   }
   
   # Query the journal
   lquery() {
       grep -ni $1 $journal
   }
   
   # Show all journal entries from today
   ltoday() {
       clear
       grep -n $(date +%Y-%m-%d) $journal
   }
   
   # On a line identified by line number, switch @todo to @done
   ldo() {
       sed -i "$1 s/@todo/@done/" $journal
       sed -i "$1 s/$/ \[COMPLETED $(date +%Y-%m-%d--%H:%M)\]/" $journal
   }

Nice things about this system: there's only one file; I'm only ever looking at the data I want to see; and there are no applications running or files open (except my terminal, I guess).