check.sh

#!/usr/bin/env bash
BASEDIR=$(dirname $0)
. $BASEDIR/functions.sh

#     step "Remounting / and /boot as read-write:"
#     try mount -o remount,rw /
#     try mount -o remount,rw /boot
#     next
#
# usecases:
# * verify an expression exits exitcode 0
# * verify a certain string occurs (with grep)
# * verify a certain string does not occur

check_vboxnet() {
	ifconfig |grep vboxnet 2>&1 > /dev/null
}

step "nmap installed"
try  which nmap
next

step "vboxnet interface must exist"
try check_vboxnet
next

functions.sh

#!/bin/bash
# this file is based directly on suggesion by John Kugelman in 
# http://stackoverflow.com/a/5196220/109305
#
#. /etc/init.d/functions
BASEDIR=$(dirname $0)
. $BASEDIR/initd_functions.sh
# Use step(), try(), and next() to perform a series of commands and print
# [  OK  ] or [FAILED] at the end. The step as a whole fails if any individual
# command fails.
#
# Example:
#     step "Remounting / and /boot as read-write:"
#     try mount -o remount,rw /
#     try mount -o remount,rw /boot
#     next
step() {
    echo -n "$@"

    STEP_OK=0
    [[ -w /tmp ]] && echo $STEP_OK > /tmp/step.$$
}

try() {
    # Check for `-b' argument to run command in the background.
    local BG=

    [[ $1 == -b ]] && { BG=1; shift; }
    [[ $1 == -- ]] && {       shift; }

    # Run the command.
    if [[ -z $BG ]]; then
        "$@"
    else
        "$@" &
    fi

    # Check if command failed and update $STEP_OK if so.
    local EXIT_CODE=$?

    if [[ $EXIT_CODE -ne 0 ]]; then
        STEP_OK=$EXIT_CODE
        [[ -w /tmp ]] && echo $STEP_OK > /tmp/step.$$

        if [[ -n $LOG_STEPS ]]; then
            local FILE=$(readlink -m "${BASH_SOURCE[1]}")
            local LINE=${BASH_LINENO[0]}

            echo "$FILE: line $LINE: Command \`$*' failed with exit code $EXIT_CODE." >> "$LOG_STEPS"
        fi
    fi

    return $EXIT_CODE
}

next() {
    [[ -f /tmp/step.$$ ]] && { STEP_OK=$(< /tmp/step.$$); rm -f /tmp/step.$$; }
    [[ $STEP_OK -eq 0 ]]  && echo_success || echo_failure
    echo

    return $STEP_OK
}

initd_functions.sh

#!/bin/bash
# -*-Shell-script-*-
#
# functions	This file contains functions to be used by most or all
#		shell scripts in the /etc/init.d directory.
#

# Get a sane screen width
[ -z "${COLUMNS:-}" ] && COLUMNS=80

# Read in our configuration
RES_COL=60
MOVE_TO_COL="echo -en \\033[${RES_COL}G"
SETCOLOR_SUCCESS="echo -en \\033[1;32m"
SETCOLOR_FAILURE="echo -en \\033[1;31m"
SETCOLOR_WARNING="echo -en \\033[1;33m"
SETCOLOR_NORMAL="echo -en \\033[0;39m"

echo_success() {
  $MOVE_TO_COL
  echo -n "["
  $SETCOLOR_SUCCESS
  echo -n $"  OK  "
  $SETCOLOR_NORMAL
  echo -n "]"
  echo -ne "\r"
  return 0
}

echo_failure() {
  $MOVE_TO_COL
  echo -n "["
  $SETCOLOR_FAILURE
  echo -n $"FAILED"
  $SETCOLOR_NORMAL
  echo -n "]"
  echo -ne "\r"
  return 1
}

echo_passed() {
  $MOVE_TO_COL
  echo -n "["
  $SETCOLOR_WARNING
  echo -n $"PASSED"
  $SETCOLOR_NORMAL
  echo -n "]"
  echo -ne "\r"
  return 1
}

echo_warning() {
  $MOVE_TO_COL
  echo -n "["
  $SETCOLOR_WARNING
  echo -n $"WARNING"
  $SETCOLOR_NORMAL
  echo -n "]"
  echo -ne "\r"
  return 1
}