1、if的语法结构if 职邗珩垃[ condition ]then statements[elif condition then statements. ..][else statements ]fi
3、字符串比较
6、脚本实例脚本一：#!/bin/shecho "挢旗扦渌;Please input a integer:"rea颊俄岿髭d integer1if [ "$integer1" -lt 30 ]then echo "The integer which you input is lower than 30."fi脚本二：if [ -f 023.txt ];then echo "file is exist"else touch 023.txtfi
