xinhu1300 发表于 2018-8-22 10:50:04

shell循环结构之while循环

  while循环
  1)
  while CONDITION; do
  statement
  statement
  
  done
  编写脚本,计算1---100的和
  #!/bin/bash
  #
  sum=0
  i=1
  while [ $i -le 100 ]; do
  let sum=$sum+$i
  let i=$i+1
  done
  echo $sum
  2)
  while true; do
  statement
  statement
  done
  #!/bin/bash
  #
  while true; do
  read -p "请输入你的选择:" choice
  if [ $choice == "q" ]; then
  break
  fi
  done
  #!/bin/bash
  #
  while true; do
  uptime
  sleep 3
  done
  3)
  while read line; do
  statement
  statement
  done < file
  #!/bin/bash
  #
  bash_num=0
  nologin_num=0
  while read line; do
  sh_name=$(echo $line | awk -F: '{print $7}')
  case $sh_name in
  /bin/bash)
  let bash_num=$bash_num+1
  ;;
  /sbin/nologin)
  let nologin_num=$nologin_num+1
  ;;
  esac
  done < /etc/passwd
  echo $bash_num
  echo $nologin_num
  util循环:
  util CONDITION; do
  statement
  statement
  done
  条件为假时,执行循环,条件为真时,结束循环

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