#!/bin/bash

# This script checks swap space available on the machine it is run on. It outputs the 
# percentage of free space or mumber of bytes free, depending on input parameters.
#
# Usage: "check_swap_osx [-h] [-V] [-v] -w WARNING(INTEGER) -c CRITICAL(INTEGER)"
#
# WARNING > CRIT
#
# WARNING and CRIT are measured in percentage or bytes
#
# Returns the nagios native status codes:
#
# Nagios Status
#
# 0 = OK (SWAP FREE more than WARNING) 1 = WARNING (SWAP FREE between
# WARNING AND CRITICAL) 2 = CRITICAL (SWAP FREE less than CRITICAL) 3
# = UNKNOWN (Wrong usage)
#
# Tested on:
# - Mac OS X 10.9.2
#
# Copyright 2012 Shu Wei Tan (webblazers@yahoo.com)
# Copyright 2014 Thom DeCarlo (pixelpshr@gmail.com)
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
# 
# Change History:
# 10/05/2012 - Version 1.0 - Shu Wei Tan (webblazers@yahoo.com)
#
# 03/01/2014 - Version 1.1 - Thom DeCarlo (pixelpshr@gmail.com)
#  Re for use on Mac OS X 10.9.2
#
version=1.1

## USAGE MESSAGE
usage() { 
cat << EOF
usage: $0 options

Check swap space on local machine.

Usage:
check_swap [-h] [-V] [-v] -w <percent_free>% -c <percent_free>%
check_swap [-h] [-V] [-v] -w <bytes_free> -c <bytes_free>

Options:
 -h, --help
    Print detailed help screen
 -V, --version
    Print version information
 -w, --warning=INTEGER
    Exit with WARNING status if less than INTEGER bytes of swap space are free
 -w, --warning=PERCENT%%
    Exit with WARNING status if less than PERCENT of swap space is free
 -c, --critical=INTEGER
    Exit with CRITICAL status if less than INTEGER bytes of swap space are free
 -c, --critical=PERCENT%%
    Exit with CRITCAL status if less than PERCENT of swap space is free
 -v, --verbose
    Show details for command-line debugging (Nagios may truncate output)

Critical trigger must be less than Warning trigger

EOF
}

VERBOSE=false

SWAP_WARN=
SWAP_CRIT=
WARN_IS_PERCENT=false
CRIT_IS_PERCENT=false
WARN_MULT=1
CRIT_MULT=1

## FETCH ARGUMENTS
while getopts "hvVw:c:" OPTION; do
        case "${OPTION}" in
                h)
                        usage
                        exit 3
                        ;;
                V)
                        echo check_swap_osx Version ${version}
                        exit 3
                        ;;
                v)
                        VERBOSE=true
                        ;;
                w)
                        SWAP_WARN=${OPTARG}
                        ;;
                c)
                        SWAP_CRIT=${OPTARG}
                        ;;
                ?)
                        usage
                        exit 3
                        ;;
        esac
done

## CHECK ARGUMENTS (WILL CHECK VALUES LATER)
if [ -z ${SWAP_WARN} ] || [ -z ${SWAP_CRIT} ] ; then
        usage
        exit 3
fi


## GET SWAP SPACE INFO FROM MACHINE
SWAP_TOTAL=$(sysctl -n vm.swapusage | awk '{print $3}')
SWAP_USED=$(sysctl -n vm.swapusage | awk '{print $6}')
SWAP_FREE=$(sysctl -n vm.swapusage | awk '{print $9}')

TOTAL_LAST_CHAR=$(echo "${SWAP_TOTAL}"| sed 's/^.*\(.\)$/\1/')
case "${TOTAL_LAST_CHAR}" in
    K)
        TOTAL_MULT=$(echo '2^10'| bc)
        SWAP_TOTAL=$(echo "${SWAP_TOTAL}"| sed 's/.$//')
        ;;
    M)
        TOTAL_MULT=$(echo '2^20'| bc)
        SWAP_TOTAL=$(echo "${SWAP_TOTAL}"| sed 's/.$//')
        ;;
    G)
        TOTAL_MULT=$(echo '2^30'| bc)
        SWAP_TOTAL=$(echo "${SWAP_TOTAL}"| sed 's/.$//')
        ;;
    *)
        ;;
esac
SWAP_TOTAL=$(echo "${SWAP_TOTAL} * ${TOTAL_MULT}" | bc)

if [ ${VERBOSE} = true ] ; then
    echo SWAP_TOTAL = ${SWAP_TOTAL}
fi

FREE_LAST_CHAR=$(echo "${SWAP_FREE}"| sed 's/^.*\(.\)$/\1/')
case "${FREE_LAST_CHAR}" in
    K)
        FREE_MULT=$(echo '2^10'| bc)
        SWAP_FREE=$(echo "${SWAP_FREE}"| sed 's/.$//')
        ;;
    M)
        FREE_MULT=$(echo '2^20'| bc)
        SWAP_FREE=$(echo "${SWAP_FREE}"| sed 's/.$//')
        ;;
    G)
        FREE_MULT=$(echo '2^30'| bc)
        SWAP_FREE=$(echo "${SWAP_FREE}"| sed 's/.$//')
        ;;
    *)
        ;;
esac
SWAP_FREE=$(echo "${SWAP_FREE} * ${FREE_MULT}" | bc)

SWAP_PERCENT_FREE=$(echo "100 * ${SWAP_FREE} / ${SWAP_TOTAL}" | bc)

if [ ${VERBOSE} = true ] ; then
    echo SWAP_FREE = ${SWAP_FREE}
    echo SWAP_PERCENT_FREE = ${SWAP_PERCENT_FREE}
fi

# NOW WE HAVE THE VALUE. DETERMINE HOW WE SHOULD TEST IT.

# Is the warning parameter a percentage, or does it have a size modifier?
WARN_LAST_CHAR=$(echo "${SWAP_WARN}"| sed 's/^.*\(.\)$/\1/')
case "${WARN_LAST_CHAR}" in
    \%)
        WARN_IS_PERCENT=true
        SWAP_WARN=$(echo "${SWAP_WARN}"| sed 's/.$//')
        ;;
    K)
        WARN_MULT=$(echo '2^10'| bc)
        SWAP_WARN=$(echo "${SWAP_WARN}"| sed 's/.$//')
        ;;
    M)
        WARN_MULT=$(echo '2^20'| bc)
        SWAP_WARN=$(echo "${SWAP_WARN}"| sed 's/.$//')
        ;;
    G)
        WARN_MULT=$(echo '2^30'| bc)
        SWAP_WARN=$(echo "${SWAP_WARN}"| sed 's/.$//')
        ;;
    *)
        ;;
esac
SWAP_WARN=$(echo "${SWAP_WARN} * ${WARN_MULT}" | bc)

if [ ${VERBOSE} = true ] ; then
    echo SWAP_WARN = ${SWAP_WARN}
    echo WARN_IS_PERCENT = ${WARN_IS_PERCENT}
fi

CRIT_LAST_CHAR=$(echo "${SWAP_CRIT}"| sed 's/^.*\(.\)$/\1/')
case "${CRIT_LAST_CHAR}" in
    \%)
        CRIT_IS_PERCENT=true
        SWAP_CRIT=$(echo "${SWAP_CRIT}" | sed 's/.$//')
        ;;
    K)
        CRIT_MULT=$(echo '2^10'| bc)
        SWAP_CRIT=$(echo "${SWAP_CRIT}" | sed 's/.$//')
        ;;
    M)
        CRIT_MULT=$(echo '2^20'| bc)
        SWAP_CRIT=$(echo "${SWAP_CRIT}" | sed 's/.$//')
        ;;
    G)
        CRIT_MULT=$(echo '2^30'| bc)
        SWAP_CRIT=$(echo "${SWAP_CRIT}" | sed 's/.$//')
        ;;
    *)
        ;;
esac
SWAP_CRIT=$(echo "${SWAP_CRIT} * ${CRIT_MULT}" | bc)

if [ ${VERBOSE} = true ] ; then
    echo SWAP_CRIT = ${SWAP_CRIT}
    echo CRIT_IS_PERCENT = ${CRIT_IS_PERCENT}
fi

# calculate how many bytes of free swap will trigger the WARN
if [ ${WARN_IS_PERCENT} = true ] ; then
    WARN_BYTES=$(echo "${SWAP_TOTAL}*${SWAP_WARN}/100.0" | bc)
else
    WARN_BYTES=${SWAP_WARN}
fi

if [ ${VERBOSE} = true ] ; then
    echo WARN_BYTES = ${WARN_BYTES}
fi

# calculate how many bytes of free swap will trigger the CRIT
if [ ${CRIT_IS_PERCENT} = true ] ; then
    CRIT_BYTES=$(echo "${SWAP_TOTAL}*${SWAP_CRIT}/100.0" | bc)
else
    CRIT_BYTES=${SWAP_CRIT}
fi

if [ ${VERBOSE} = true ] ; then
    echo CRIT_BYTES = ${CRIT_BYTES}
fi


## CHECK ARGUMENTS
if [ -z ${SWAP_WARN} ] || [ -z ${SWAP_CRIT} ] || [ ${SWAP_WARN} -lt ${SWAP_CRIT} ] ; then
        usage
        exit 3
fi


## CHECK SWAP SPACE ON MACHINE
if (( ${CRIT_IS_PERCENT} == true )) && (( $(bc <<< "${SWAP_PERCENT_FREE} < ${SWAP_CRIT}") == 1 ))
then
        ## SWAP IS IN CRITICAL STATE
        LINE="CRITICAL! Swap free: ${SWAP_PERCENT_FREE}% | swap_free=${SWAP_PERCENT_FREE}%;${SWAP_WARN}%;${SWAP_CRIT}%;"
        echo $LINE
        exit 2
elif (( ${CRIT_IS_PERCENT} == false )) && (( $(bc <<< "${SWAP_FREE} < ${CRIT_BYTES}") == 1 ))
then
        ## SWAP IS IN CRITICAL STATE
        LINE="CRITICAL! Swap free: ${SWAP_FREE}B | swap_free=${SWAP_FREE}B;${WARN_BYTES}B;${CRIT_BYTES}B;"
        echo $LINE
        exit 2
elif (( ${WARN_IS_PERCENT} == true )) && (( $(bc <<< "${SWAP_PERCENT_FREE} < ${SWAP_WARN}") == 1 ))
then
        ## SWAP IS IN WARNING STATE
        LINE="WARNING! Swap free: ${SWAP_PERCENT_FREE}% | swap_free=${SWAP_PERCENT_FREE}%;${SWAP_WARN}%;${SWAP_CRIT}%;"
        echo $LINE
        exit 1
elif (( ${WARN_IS_PERCENT} == false )) && (( $(bc <<< "${SWAP_FREE} < ${WARN_BYTES}") == 1 ))
then
        ## SWAP IS IN WARN STATE
        LINE="WARNING! Swap free: ${SWAP_FREE}B | swap_free=${SWAP_FREE}B;${WARN_BYTES}B;${CRIT_BYTES}B;"
        echo $LINE
        exit 1
elif (( ${WARN_IS_PERCENT} == true )) && (( $(bc <<< "${SWAP_PERCENT_FREE} >= ${SWAP_WARN}") == 1 ))
then
	## SWAP IS OK
        LINE="OK! Free Swap space: ${SWAP_PERCENT_FREE}% | swap_free=${SWAP_PERCENT_FREE}%;${SWAP_WARN}%;${SWAP_CRIT}%;"
        echo $LINE
        exit 0
elif (( ${WARN_IS_PERCENT} == false )) && (( $(bc <<< "${SWAP_FREE} >= ${WARN_BYTES}") == 1 ))
then
	## SWAP IS OK
        LINE="OK! Free Swap space: ${SWAP_FREE}B | swap_free=${SWAP_FREE}B;${WARN_BYTES}B;${CRIT_BYTES}B;"
        echo $LINE
        exit 0
else
	## SHOULD NEVER REACH THIS POINT, MUST BE USAGE :)
        usage
        exit 3
fi