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How do I make an init.d script wait for a startup/shutdown message to appear in a log file, but time out if it takes too long?

tail -f | grep -m 1 should do the trick. There are ways to make the tail -f time out. And (at least in my opinion) the tail should terminate with a broken pipe when the grep stops running, but it doesn't; the tail -f just keeps running.

Though it's likely I'm doing something wrong, I do have a workaround:

#!/bin/dash

(sleep 20 2>/dev/null)&
TIMER=$!

tail -n 0 -f log --pid $TIMER | \
    (R=`grep -cm 1 searchstring`; kill $TIMER 2>/dev/null; exit $R)

RESULT=$?