【鸟哥的私房菜摘录】SHELL脚本编程

bash相关环境配置文件在~/.bashrc

标准模板范例如下：

#!/bin/bash# Program:#       This program shows "Hello World!" in your screen.# History:# 2012.05.15 famousDT First release# main environment declarePATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/root/bin/:/home/famousDT/famousDT/scriptsexport PATH#++++++++++++++++++++++++++++++++++++++++++++++#user inputread -p "first name: " firstread -p "last name: " last#"-e" let '\' be usefullecho -e "\n Your full name is : $first $last"#++++++++++++++++++++++++++++++++++++++++++++++#creates three files, which named by user's#input and date command.read -p "input your filename: " fileuser#if fileuser not right, replace it by "filename"filename=${fileuser:-"filename"}date1=$(date --date='2 days ago' +%Y%m%d)date2=$(date --date='1 days ago' +%Y%m%d)date3=$(date +%Y%m%d)file1=${filename}${date1}file2=${filename}${date2}file3=${filename}${date3}touch "$file1"touch "$file2"touch "$file3"#used for "$?" as return value for callerexit 0

数值运算，只能做整数计算

#++++++++++++++++++++++++++++++++++++++++++++++#user inputs 2 integer numbers a, b, return a*bread -p "input first: " firstread -p "input second: " secondtotal=$(($first * $second));echo -e "\nThe result of $first * $second = $total"

累加计算1+2+……100

#++++++++++++++++++++++++++++++++++++++++++++++s=0end=100for ((i=1;i<=$end;i=i+1))dos=$(($s+$i))doneecho $s

直接执行shell脚本是在子进程中执行的，如果用source来执行脚本，则在父进程中执行，在子进程中设置的变量在父进程中有效。这也是为什么不用注销系统而要让某些写入~/.bashrc的设置生效，需要使用source ~/.bashrc而不能用bash ~/.bashrc