_note.sh

#!/bin/sh

# Note file
note_file=~/_notes.md

# Create Note file if it does not exist
if [ ! -f "$note_file" ]; then
    touch $note_file
fi

# Get Date
date=`date '+%Y-%m-%d'`

# Get line number in notes for today (2019-09-23)
date_line=`grep -n $date $note_file | sed -nE 's/([0-9]):.*/\1/p'`

# If the line does not exist
# append today's (YYYY-MM-DD) to the end of the file, and open at the end of the file
if [ -z "$date_line" ]; then
    echo "## $date\n" >> $note_file
    line_number=$(($((`grep -n $date $note_file | sed -nE 's/([0-9]):.*/\1/p'`))+1))
    vim $note_file +$line_number
    exit
fi

# Otherwise, open the file with vim at date_line + 1
vim $note_file +$(($date_line+1))