shell笔记day08

while循环

#!/bin/bash
while true 
do
    load=`w|head -1|awk -F 'load average:' '{print $2}' | cut -d. -f1`
    if [$load -gt 10 ]
    then 
	/usr/local/sbin/mail.py [email protected] "load high" "$load"
    fi
    sleep 30
done

适用于反复输入内容

#!/bin/bash
while :
do
  read -p "please input a newber: " n
  if [ -Z "$n" ]
  then 
	echo "你需要输入一个数字"
	continue
  fi
  n1=`echo $n|sed 's/[-0-9]//g'`
  if [ ! -z $n1 ]
  then
	echo "你只能输入一个纯数字"
	continue
  fi
  break
done
echo $n

break使用

for i in `seq 1 5`
do
   echo $i
   if [ $i -eq 3 ]
   then 
      break
   fi
   echo $i
done

循环中用break跳出！

continue结束循环

for i in `seq 1 5`
do
   echo $i
   if [ $i -eq 3 ]
   then 
      continue
   fi
   echo $i
done

exit直接退出

#!/bin/bash
for i in `seq 1 5`
do
  echo $i
  if [ $i -eq 3 ]
  then
     exit 
  fi
  echo $i
done 
echo aaaaa