Print clipboard changes to stdout with timestamp and new content. Works only on OS X (or wherever you have something equivalent to `pbpaste` installed).

cliptracker.sh

#!/usr/bin/env bash

# Tracks contents of the clipboard by printing changes to
# stdout with a timestamp

last=$(pbpaste)

# Check if the clipboard content has changed, and if it has
# output the new contents with a timestamp
sample() {
	current=$(pbpaste)
	if [ "$current" != "$last" ]; then
		printf "$(date -u +"%Y-%m-%d %H:%M:%S"): \"$current\"\n";
		last=$current;
	fi
}

# Print the clipboard at the start
printf "Started tracking\n"
printf "$(date -u +"%Y-%m-%d %H:%M:%S"): \"$(pbpaste)\"\n"

# Main loop, checks for changes each second
while true; do
	sample;
	sleep 1;
done;