Linux Memory Check Script in Bash. Works with Nagios and Icinga/Icinga 2

check_memory.sh

#!/bin/bash

#13:16 $ ./check_memory.sh 
#OK - Used: 197/3953 (4%);|'Memory Used'=197MB;3360;3755;4053
#Swap Usage: 0/3905 (0%);|'Swap Used'=0MB;3319;3709;4005 

MEMTOTAL=$(free | awk '/Mem/ {printf("%d",$2/1024)}')
SWAPTOTAL=$(free | awk '/Swap/ {printf("%d", $2 / 1024)}')

# Get the memory usage in %
MEMUSED=$(free | awk '/Mem/ {printf("%d",($3-$6-$7)/1024)}')
MEMUSEDPERCENT=$(free | awk '/Mem/ {printf("%d", ($3-$6-$7)/$2 * 100)}')

# Get swap usage in %
SWAPUSED=$(free | awk '/Swap/ {printf("%d", $3 / 1024)}')
SWAPUSEDPERCENT=$(free | awk '/Swap/ {if($3 == 0){printf("%d", 0)} else{printf("%d", $3/$2 * 100)}}')

# Total Values (for perf data)
mem_warn=$(echo | awk -v memtotal=$MEMTOTAL '{printf("%d", memtotal * .85)}')
mem_crit=$(echo | awk -v memtotal=$MEMTOTAL '{printf("%d", memtotal * .95)}')
mem_max=$(expr $MEMTOTAL + 100)

swap_warn=$(echo | awk -v swaptotal=$SWAPTOTAL '{printf("%d", swaptotal * .85)}')
swap_crit=$(echo | awk -v swaptotal=$SWAPTOTAL '{printf("%d", swaptotal * .95)}')
swap_max=$(expr $SWAPTOTAL + 100)

output="Used: $MEMUSED/$MEMTOTAL ($MEMUSEDPERCENT%);|'Memory Used'=${MEMUSED}MB;${mem_warn};${mem_crit};${mem_max}"
swap_output="Swap Usage: $SWAPUSED/$SWAPTOTAL (${SWAPUSEDPERCENT}%);|'Swap Used'=${SWAPUSED}MB;${swap_warn};${swap_crit};${swap_max} "
# OK
if [ $MEMUSEDPERCENT -le 85 ]
then
  echo "OK - $output"
  echo "$swap_output"
  exit 0
elif [ $MEMUSEDPERCENT -ge 85 ] && [ $MEMUSEDPERCENT -le 95 ]
then
  echo "WARNING - $output"
  echo "$swap_output"
  exit 1
elif [ $MEMUSEDPERCENT -gt 95 ]
then
  echo "CRITICAL - $output"
  echo "$swap_output"
  exit 2
else
  echo "UNKNOWN - $output"
  echo "$swap_output"
  exit 3
fi