pre-commit.sh

#!/usr/bin/bash
#
# Git pre-commit hook for obsidian.ms or other collections of markdown files.
# This hook works with obsidian-git https://github.com/denolehov/obsidian-git
#
# An hook script to verify what is about to be committed.
# This script is called by "git commit" with no arguments.
# The hook should exit with non-zero status after issuing an appropriate message if it wants to stop the commit.
#
# Usage: Remove the .sh file extension when you put the script in your hooks folder!
#
# Purposes: 
# Removes empty lines at the end of the file, leaving one.
# Removes trailing empty space at the end of a lines.
#
# Information used to create this script:
# https://eng.wealthfront.com/2011/03/08/corrective-action-with-gits-pre-commit/
# http://stackoverflow.com/questions/13223868/how-to-stage-line-by-line-in-git-gui-although-no-newline-at-end-of-file-warnin
# https://unix.stackexchange.com/questions/552188/how-to-remove-empty-lines-from-beginning-and-end-of-file

git diff-index --name-only --cached HEAD -z |
while read -d $'\0' f
do
  echo $f
  # Only examine markdown text files
  if [[ "$f" =~ [.](md)$ ]]   # conf|css|erb|html|js|json|log|properties|rb|ru|txt|xml|yml|h|m
  then
    # Detect two trailing empty lines at the end of file
    if [ -z $(tail -n2 "$f") ]
    then
      echo trailing empty lines: $f
      # remove blank lines from the begin of file
      # sed -i '/./,$!d' "$f"
      # remove blank lines from the end of file:
      sed -i -e :a -e '/^\n*$/{$d;N;ba' -e '}' "$f"
      # remove blank lines from the begin and end of file
      # sed -i -e '/./,$!d' -e :a -e '/^\n*$/{$d;N;ba' -e '}' "$f"
      # echo >> $f
      git add "$f"
    fi
    # Detect trailing whitespace at the end of lines
    if grep -q "[[:blank:]]$" "$f"
    then
      echo trailing ws: $f
       # Remove trailing whitespace from the end of lines
       sed -i"" -e $'s/[ t]*$//g' "$f"
       git add "$f"
    fi
  fi
done