live.sh

#!/bin/bash

# Color codes for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m' # No Color

print_usage() {
  SCRIPT_NAME=$(basename "$0")
  echo "Description"
  echo ""
  echo "Usage: $SCRIPT_NAME <path1> [path2 ...] -- <command>"
  echo "Example: $SCRIPT_NAME src/ lib/ -- npm test"
  echo "Parameters:"
  echo "  -h, --help  Show this help message"
  exit "$1"
}

if [ $# -lt 3 ]; then
  print_usage 1
fi

COMMAND=""
PARSING_PATHS=true
PATHS=()
for arg in "$@"; do
  if [ "$arg" = "--" ]; then
    PARSING_PATHS=false
    continue
  fi

  if [ "$PARSING_PATHS" = true ]; then
    PATHS+=("$arg")
  else
    if [ -z "$COMMAND" ]; then
      COMMAND="$arg"
    else
      COMMAND="$COMMAND $arg"
    fi
  fi
done

if [ ${#PATHS[@]} -eq 0 ]; then
  echo -e "${RED}Error: No paths specified${NC}"
  print_usage 2
fi

if [ -z "$COMMAND" ]; then
  echo -e "${RED}Error: No command specified${NC}"
  print_usage 3
fi

for path in "${PATHS[@]}"; do
  if [ ! -e "$path" ]; then
    echo -e "${RED}Error: Path does not exist: $path${NC}"
    exit 1
  fi
done

log() { printf '%s %s\n' "$(date '+%Y-%m-%d %H:%M:%S')" "$1"; }

SNAP_BEFORE=$(mktemp)
SNAP_AFTER=$(mktemp)

cleanup() {
  rm -f "$SNAP_BEFORE" "$SNAP_AFTER"
}

trap printout SIGINT
printout() {
  echo ""
  1>&2 echo "Watch path terminated forcefully"
  cleanup
  exit
}
trap cleanup EXIT

eval "${COMMAND}"

while true
do
  ls -lRT "${PATHS[@]}" > "$SNAP_BEFORE" 2>&1

  # md5 collapses the listing to one line so it always fits watch's
  # visible screen — watch -g only compares what is drawn on screen
  watch -t -g "ls -lRT ${PATHS[*]} | md5" > /dev/null

  ls -lRT "${PATHS[@]}" > "$SNAP_AFTER" 2>&1
  CHANGED=$(diff "$SNAP_BEFORE" "$SNAP_AFTER" \
    | grep -E '^[<>] [-dl]' \
    | sed -E 's/^[<>] [^ ]+ +[^ ]+ +[^ ]+ +[^ ]+ +[^ ]+ +[A-Za-z]{3} +[0-9]+ +[0-9:]+ +[0-9]{4} +//' \
    | sort -u)

  if [ -n "$CHANGED" ]; then
    printf "\n===================\n"
    log "changed: $CHANGED"
    printf "\n-------------------\n"
  fi
  eval "${COMMAND}"
done