将某一行存储下来

#!/bin/sh
# ipcs> ipcs.log
#cat ipcs.log|grep 68

 if [ ! -f "ipcs.log" ]; then
 echo "ipcs.log not exist! ............"
 fi
 while true

 do
 ipcs> ipcs.log
 #cat ipcs.log
 mm=$(cat ipcs.log|grep 68|awk '{print $6}')
 if [ $mm -ne 0 ];then
 echo ${mm} >> tmp
 fi
 sleep 1
 done