madasi

#!/bin/bash
# Description of script

# Required program(s)
req_progs=(prog1 prog2)
for p in ${req_progs[@]}; do
  hash "$p" 2>&- || \
  { echo >&2 " Required program \"$p\" not installed."; exit 1; }
done

madasi

#!/bin/bash
# Description of script

# Display usage if no parameters given
if [[ -z "$@" ]]; then
  echo " ${0##*/} <input> - description"
  exit
fi

# Required program(s)