Linux系统内存机制:在linux中有这么一种思想，内存不用白不用，因此它尽可能的cache和buffer一些数据，以方便下次使用。但实际上这些内存也是可以立刻拿来使用的。所以 空闲内存=free+buffers+cached
check_mem.sh 这个监控脚本是网上找来的.他的取的内存值是free -m 出来的Mem: total userd free的三个值. 按照上面的说法.这样的监控方式不对.所以我修改了下这个脚本.很简单.主要是修改了这两个值:
# Total memory used
used=`free -m | head -3 |tail -1 |awk '{print $3}'`
# Calc total minus used
free=`free -m | head -3 |tail -1 |awk '{print $4}'`
check_mem.sh
#!/bin/bash
USAGE="`basename $0` [-w|--warning]<percent free> [-c|--critical]<percent free>"
THRESHOLD_USAGE="WARNING threshold must be greater than CRITICAL: `basename $0` $*"
calc=/tmp/memcalc
percent_free=/tmp/mempercent
critical=""
warning=""
STATE_OK=0
STATE_WARNING=1
STATE_CRITICAL=2
STATE_UNKNOWN=3
# print usage
if [[ $# -lt 4 ]]
then
echo ""
echo "Wrong Syntax: `basename $0` $*"
echo ""
echo "Usage: $USAGE"
echo ""
exit 0
fi
# read input
while [[ $# -gt 0 ]]
do
case "$1" in
-w|--warning)
shift
warning=$1
;;
-c|--critical)
shift
critical=$1
;;
esac
shift
done
# verify input
if [[ $warning -eq $critical || $warning -lt $critical ]]
then
echo ""
echo "$THRESHOLD_USAGE"
echo ""
echo "Usage: $USAGE"
echo ""
exit 0
fi
# Total memory available
total=`free -m | head -2 |tail -1 |gawk '{print $2}'`
# Total memory used
used=`free -m | head -3 |tail -1 |awk '{print $3}'`
# Calc total minus used
free=`free -m | head -3 |tail -1 |awk '{print $4}'`
# normal values
#echo "$total"MB total
#echo "$used"MB used
#echo "$free"MB free
# make it into % percent free = ((free mem / total mem) * 100)
echo "5" > $calc # decimal accuracy
echo "k" >> $calc # commit
echo "100" >> $calc # multiply
echo "$free" >> $calc # division integer
echo "$total" >> $calc # division integer
echo "/" >> $calc # division sign
echo "*" >> $calc # multiplication sign
echo "p" >> $calc # print
percent=`/usr/bin/dc $calc|/bin/sed 's/^\./0./'|/usr/bin/tr "." " "|/usr/bin/gawk {'print $1'}`
#percent1=`/usr/bin/dc $calc`
#echo "$percent1"
if [[ "$percent" -le $critical ]]
then
echo "CRITICAL - $free MB ($percent%) Free Memory"
exit 2
fi
if [[ "$percent" -le $warning ]]
then
echo "WARNING - $free MB ($percent%) Free Memory"
exit 1
fi
if [[ "$percent" -gt $warning ]]
then
echo "OK - $free MB ($percent%) Free Memory"
exit 0
fi
