Copies a file to another file with yesterday's date - used for a rudimentary todo history tracker when I work

gistfile1.txt

# Get yesterday's date (different between Mac and Linux)
if [[ "$OSTYPE" == "darwin"* ]]; then
	yesterday=`date -v-1d +%F`
else
	yesterday=$(date -d "yesterday 13:00" +'%Y%m%d')
fi

# Construct the filename
dest=past-$yesterday.md

# Make sure the script hasn't already been run today
if [ -e $dest ]; then
	echo "ERROR: todo already moved on"
else
	cp -n _today.md $dest
fi

cd -