#!/bin/bash
set -u

file_contains() {
  local file="$1"
  local searchword="$2"
  local result=$(grep -F "${searchword}" "${file}")
  if [[ $? != 0 ]]; then
    # Nothing found
    return 1
  fi

  return 0
}
{
  file_contains "/etc/hosts" "foo"
  exit "$?"
}