lock-quote

#!/usr/bin/env bash
# lock-quote by Amory Meltzer
# Stochastically change the login/lock screen message in macOS using a quotes file

function help {
    cat <<END_HELP
Usage: $(basename "$0") [-fsnhH]

  -f		Provide a path to a file of quotes, one per line.  Overrides LOCK_SCREEN_QUOTES.
  -s		Show the current text used on the login/lock screen.  No sudo required.  Overrides -n.
  -n		Show a quote but don't use it.  No sudo required.
  -h -H		This help.
END_HELP
}

# Set the quotes file
# Default to using environment variable
if [[ -n "$LOCK_SCREEN_QUOTES" ]]; then
    quotefile="$LOCK_SCREEN_QUOTES"
fi

while getopts 'f:snhH' opt; do
    case $opt in
	f) quotefile=$OPTARG;;
	s) defaults read /Library/Preferences/com.apple.loginwindow.plist LoginwindowText
	   exit 0;;
	n) dryrun=1;;
	h|H) help
	     exit 0;;
	*) printf "Invalid option provided, try %s -h\n" "$0" >&2
	   exit 1;;
    esac
done

if [[ ! -e "$quotefile" ]]; then
    # Get this script's directory: http://stackoverflow.com/a/246128/2521092
    DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
    quotefile=$DIR/lockscreen_quotes.txt
fi


shuf_command="shuf"
# macOS doesn't have shuf, but coreutils installs gshuf
if [[ ! $(command -v 2>/dev/null "$shuf_command") ]]; then
    shuf_command="gshuf"
    # If that doesn't exist, approximate it via perl
    # https://stackoverflow.com/a/6511327/2521092
    if [[ ! $(command -v 2>/dev/null "$shuf_command") ]]; then
	function gshuf() {
	    perl -MList::Util=shuffle -e 'print shuffle(<>);' "$@";
	}
    fi
fi
quote=$($shuf_command "$quotefile" | head -n 1 | tr -d '\n')
quote=$(sed -Ee 's/\[|\]//g; s/\"//g; s/ - / \]- /' <<< "$quote" | tr ']' '\n')

if [[ -n "$dryrun" ]]; then
    echo "$quote"
    exit 0
fi

defaults write /Library/Preferences/com.apple.loginwindow.plist LoginwindowText "$quote"