Essential shell scripting

arguments.sh

# Parsing and processing script arguments
while [ $# -gt 0 ]; do
  case $1 in 
    -p)
      shift
      PORT=$1
      ;;
    --pbuilder-basetgz=*)
      BASETGZ="$(echo $1 | cut -d = -f 2)"
      ;;
    --help|-h)
      usage
      exit
      ;;
    *) 
      usage # All other parameters 
      exit 1
  esac 
  shift 
done

log.sh

# A function to generate script logs with timestamp
# Usage:
#  log "$PROGRAM: start"
log() { 
  echo [`date +%Y-%m-%d\ %H:%M:%S`] $* 
}