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