Shell Programming and Scripting

 # "curl_args" contains "-x $2" and gets set if $2 exists
curl ${curl_args} "$1" &> /dev/null

if [ $? == 0 ]; then
   if [ "$#" == 1 ]; then
      printf "OK - able to connect to $1\n"
      exit 0
   elif [ "$#" == 2 ]; then
      printf "OK - able to connect to $1 from $2\n"
      exit 0
   fi
else
   if [ "$#" == 1 ]; then
      printf "CRITICAL - unable to connect to $1\n"
      exit 1
   elif [ "$#" == 2 ]; then
      printf "CRITICAL - unable to connect to $1 from $2\n"
      exit 1
   fi

# if we specify a proxy on $2, add the -x flag to curl
if [ "$proxy" ]; then
  # the whitespace is important
  curl_args+=" -x $2"
  exit_msg+=" via $proxy"
fi

usage() {
  printf "$(basename $0) URL [proxy]\n"
  exit 0
}

exit_ok() {
  printf "OK - $1"
  exit 0
}

exit_fail() {
  printf "FAILED - $1"
  exit 1
}

curl_cmd="curl ${curl_args} $url"
case $# in
  1) $curl_cmd &>/dev/null && exit_ok "$exit_msg" || exit_fail "$exit_msg"
     ;;
  2) $curl_cmd &>/dev/null && exit_ok "$exit_msg" || exit_fail "$exit_msg"
     ;;
  *) usage
     ;;
esac

curl_args="--fail --max-time 3"


case ${#@} in
1)	url="$1"
	exit_msg="connecting to $url"
	;;
2)	url="$1"
	curl_args="$curl_args -x \"$2\""	# The 'inner' quotes needs escape so they are there when the variable is reused
	exit_msg="connecting to $url via $2"
	;;
esac

curl $curl_args "$url"
ret=$?

[[ 0 = $ret ]] && \
	exit_msg="SUCCESS - $exit_msg" || \
	exit_msg="FAILURE - $exit_msg"

echo "$exit_msg"
exit $ret

[[ 0 = $ret ]] && \
	exit_msg="SUCCESS - $exit_msg" || \
	exit_msg="FAILURE - $exit_msg"

var=${1:-default-value}

my_msg(){ echo "${1:-some string i dont care} ; return 1 ; }
my_msg
ret=$?
echo $ret
exit $ret