1. 创建可执行文件 t2.sh 并打印 "hello world!"
xiluhua@localhost ~ $ mkdir tscripts xiluhua@localhost ~ $ cd tscripts/ xiluhua@localhost ~/tscripts $ echo \'#!/bin/bash\' >> t2.sh xiluhua@localhost ~/tscripts $ echo \'echo "hello world!"\' >>t2.sh xiluhua@localhost ~/tscripts $ chmod +x * xiluhua@localhost ~/tscripts $ ./t2.sh hello world!
2. 运行可执行文件的 3中方法
xiluhua@localhost ~/tscripts $ ./t2.sh hello world! xiluhua@localhost ~/tscripts $ sh t2.sh hello world! xiluhua@localhost ~/tscripts $ /bin/sh t2.sh hello world!
3. 使用变量
xiluhua@localhost ~/tscripts $ name=zhangsan xiluhua@localhost ~/tscripts $ echo $name zhangsan xiluhua@localhost ~/tscripts $ echo ${name} zhangsan xiluhua@localhost ~/tscripts $
变量名外面的花括号是可选的，可加可不加，加花括号是为了帮助解释器识别变量的边界
4. for 循环打印 java c c++ php scala，体会 ${} 的作用
#!/bin/bash for skill in java c c++ php scala;do echo "I am good at $skill" done echo "=======================================" for skill in java c c++ php scala;do echo "I am good at $skillScript" done echo "=======================================" for skill in java c c++ php scala;do echo "I am good at ${skill}Script" done
5. 只读变量，unset 不能取消
xiluhua@localhost ~/tscripts $ name=jack xiluhua@localhost ~/tscripts $ readonly name xiluhua@localhost ~/tscripts $ echo $name jack xiluhua@localhost ~/tscripts $ name=Tom -bash: name: readonly variable xiluhua@localhost ~/tscripts $ unset name -bash: unset: name: cannot unset: readonly variable xiluhua@localhost ~/tscripts $
6. 非只读变量可以取消，取消后打印为空
xiluhua@localhost ~/tscripts $ unname=Jerry xiluhua@localhost ~/tscripts $ unset unname xiluhua@localhost ~/tscripts $ echo $unname
7. 单引号
①. 单引号里的任何字符都原样输出，单引号变量中的变量是无效的； ②. 单引号字符串中不能出现单引号，对单引号使用转义符后也不行 xiluhua@localhost ~ $ name=\'Leo\' xiluhua@localhost ~ $ echo \'$name\' $name xiluhua@localhost ~ $ echo \'$\'name\' >
8. 双引号
①. 双引号里可以有变量 ②. 双引号里可以出现转义字符 xiluhua@localhost ~ $ echo "I am $name" I am Leo xiluhua@localhost ~ $ echo "\\I am $name \\" \I am Leo \
9. 拼接字符串
xiluhua@localhost ~ $ echo "He is $name" He is Leo xiluhua@localhost ~ $ echo "$name is handsome"! Leo is handsome! xiluhua@localhost ~ $ echo "$name is handsome!" -bash: !": event not found
10. 获取字符串长度
xiluhua@localhost ~ $ echo ${#name} 3
11. 提取字符串
xiluhua@localhost ~ $ echo ${name:0:2}
Le
12. 查找子字符串
xiluhua@localhost ~ $ expr index $name e 2
13. 数组
bash支持一维数组（不支持多维数组），并且没有限定数组的大小。
类似与C语言，数组元素的下标由0开始编号。获取数组中的元素要利用下标，下标可以是整数或算术表达式，其值应大于或等于0。
14. 声明数组并打印一
xiluhua@localhost ~ $ arr=(a b c) xiluhua@localhost ~ $ echo $arr a xiluhua@localhost ~ $ echo ${arr[0]} a xiluhua@localhost ~ $ echo ${arr[2]} c xiluhua@localhost ~ $ echo ${arr[@]} a b c
15. 声明数组并打印二
xiluhua@localhost ~ $ arr=() xiluhua@localhost ~ $ echo ${arr[@]} xiluhua@localhost ~ $ arr[0]=x xiluhua@localhost ~ $ echo ${arr[0]} x xiluhua@localhost ~ $ arr[1]=y xiluhua@localhost ~ $ arr[2]=z xiluhua@localhost ~ $ echo ${arr[@]} # 打印数组全部内容 x y z xiluhua@localhost ~ $ echo ${arr[*]} # 打印数组全部内容 x y z
16. 获取数组长度
xiluhua@localhost ~ $ echo ${#arr[@]} 3
17. 获取数组单个元素的长度
xiluhua@localhost ~ $ arr[3]=yes xiluhua@localhost ~ $ echo ${arr[3]} yes xiluhua@localhost ~ $ echo ${#arr[3]} 3
18. shell 传递参数
#!/bin/bash # auth: xiluhua # date: 2017-01-14 echo \'args 0,file name: \'$0 echo \'args 1: \'$1 echo \'args 2: \'$2 echo \'args 3: \'$3
19. 特殊字符
#!/bin/bash # auth: xiluhua # date: 2017-01-14 echo \'shell exercise\' echo \'first arg: \'$1 echo \'args total number: \'$# echo \'args are: \'$* echo \'current process id: \'$$ echo \'the last proess id run in the background: \'$! echo \'args are: \'$@ echo \'shell options: \'$- echo \'command run status: \'$?
20. $* 与$@ 的区别
相同点：都是引用所有参数。 不同点：只有在双引号中体现出来。假设在脚本运行时写了三个参数 1、2、3，， "*" 等价于 "1 2 3"（传递了一个参数）， "@" 等价于 "1" "2" "3"（传递了三个参数）
21. $* 与$@ 的区别实例
#!/bin/bash # auth: xiluhua # date: 2017-01-14 echo \'--- $* DEMO ---\' for i in "$*";do echo \'i: \'$i done echo \'--- $@ DEMO ---\' for i in "$@";do echo \'i: \'$i done
22. 新建可执行文件
sbash=\'#!/bin/bash\' sauth=\'# auth: xiluhua\' sdate="# date: $(date +%Y-%m-%d)" shead="$sbash\n$sauth\n$sdate"
23. expr
原生bash不支持简单的数学运算，但是可以通过其他命令来实现，例如 awk 和 expr，expr 最常用。
expr 是一款表达式计算工具，使用它能完成表达式的求值操作。
- 表达式和运算符之间要有空格，例如 2+2 是不对的，必须写成 2 + 2，这与我们熟悉的大多数编程语言不一样。
- 完整的表达式要被 ` ` 包含，注意这个字符不是常用的单引号，在 Esc 键下边。
例如，两个数相加(注意使用的是反引号 ` 而不是单引号 \')：
xiluhua@localhost ~/tscripts $ expr 2 + 2 4 xiluhua@localhost ~/tscripts $ sum=`expr 2 + 2` xiluhua@localhost ~/tscripts $ echo $sum 4
24. expr 加减乘除运算
xiluhua@localhost ~/tscripts $ a=20 xiluhua@localhost ~/tscripts $ b=10 xiluhua@localhost ~/tscripts $ sum=`expr $a + $b` xiluhua@localhost ~/tscripts $ echo $sum 30 xiluhua@localhost ~/tscripts $ diff=`expr $a - $b` xiluhua@localhost ~/tscripts $ echo $diff 10 xiluhua@localhost ~/tscripts $ prod=`expr $a \* $b` xiluhua@localhost ~/tscripts $ echo $prod 200 xiluhua@localhost ~/tscripts $ odd=`expr $a / $b` xiluhua@localhost ~/tscripts $ echo $odd 2
25. expr 和算术运算符实例
注意：乘号(*)前边必须加反斜杠(\)才能实现乘法运算；
#!/bin/bash # auth: xiluhua # date: 2017-01-14 a=20 b=10 echo \'--- expr DEMO ---\' echo \'a=20\' echo \'b=10\' sum=`expr $a + $b` dif=`expr $a - $b` pro=`expr $a \* $b` odd=`expr $a / $b` echo \'sum: \'$sum echo \'dif: \'$dif echo \'pro: \'$pro echo \'odd: \'$odd if [ $a == $b ] then echo \'a equal b\' fi if [ $a != $b ] then echo a "don\'t equal b" fi
26. 逻辑运算符
#!/bin/bash # auth: xiluhua # date: 2017-01-14 a=20 b=10 echo \'--- bool operators DEMO ---\' echo \'a=20\' echo \'b=10\' if [ $a != $b ] then echo \'a !equal b\' else echo \'a equal b\' fi if [ $a -gt $b -a $a -lt 30 ] then echo \'a gt 10 but lt 30\' else echo \'! ag 10 but lt 30\' fi if [ $b -eq 10 -o $b -gt 9 ] then echo \'b ge 9\' else echo \'!b ge 9\' fi
26. 字符串运算符
#!/bin/bash # auth: xiluhua # date: 2017-01-14 a=abc b=efg c=\'\' echo "--- string DEMO ---" echo "a=abc" echo "b=efg" if [ $a = $b ] then echo "a eq b" else echo "a !eq b" fi if [ $a != $b ] then echo "a !eq b" else echo "a eq b" fi if [ -z $a ] then echo "a\'s length is 0" else echo "a\'s length is ${#a}" fi if [ -z $c ] then echo "c\'s length is 0" else echo "c\'s length is ${#c}" fi if [ -n $a ] then echo "a\'s length is ${#a}" else echo "a\'s length is 0" fi if [ -n $c ] then echo "c\'s length is ${#c}" else echo "c\'s length is 0" fi if [ $a ] then echo "a\'s length is ${#a}" else echo "a\'s length is 0" fi if [ $c ] then echo "c\'s length is ${#c}" else echo "c\'s length is 0" fi
27. 关系运算符
#!/bin/bash # auth: xiluhua # date: 2017-01-14 file=\'/home/xiluhua/tscripts\' echo \'--- file test operators DEMO ---\' echo $file if [ -e $file ] then echo "$file is exist" else echo "$file is !exist" fi if [ -d $file ] then echo "$file is a directory" fi if [ -f $file ] then echo "$file is a file" fi if [ -s $file ] then echo "$file is empty" fi if [ -r $file ] then echo "$file is readable" else echo "$file is !readable" fi if [ -w $file ] then echo "$file is writable" else echo "$file is !writable" fi if [ -x $file ] then echo "$file is excecutable" else echo "$file is !excecutable" fi
28. echo 显示转义字符
echo "\"It is a test\""
29. echo 开启换行
xiluhua@localhost ~/tscripts $ echo -e "Tom \n is from China" Tom is from China
30. echo 不开启换行
#!/bin/bash # auth: xiluhua # date: 2017-01-14 echo -e "Tom is from China, \c" echo "he is programmer."
31. printf
#!/bin/bash # auth: xiluhua # date: 2017-01-14 printf "%-10s %-8s %-10s\n" name gender weight[kg] printf "%-10s %-8s %-4.2f\n" Jack male 68.1234 printf "%-10s %-8s %-4.2f\n" Tom male 78.6512 printf "%-10s %-8s %-4.2f\n" Susan female 80
32. printf
%s %c %d %f都是格式替代符 %-10s 指一个宽度为10个字符（-表示左对齐，没有则表示右对齐），任何字符都会被显示在10个字符宽的字符内，如果不足则自动以空格填充，超过也会将内容全部显示出来。 %-4.2f 指格式化为小数，其中.2指保留2位小数。
33. while (1)
#!/bin/bash # auth: xiluhua # date: 2017-01-15 n1=$1 echo \'--- while DEMO ---\' echo \'n1=$n1\' while (( $n1 <= 5 )) do echo $n1 n1=`expr $n1 + 1` # 等同于 let \'n1++\' done
34. while (2)
#!/bin/bash # auth: xiluhua # date: 2017-01-15 while true do read -p \'please input a film: \' film if [ -z $film ] then echo > /dev/null else if [ $film = \'q\' ] then exit fi if [ $film = \'ironman\' ] then echo $film\' is a good film!\' exit 0; else echo \'this film is not good enough\' fi fi done
35. until
#!/bin/bash # auth: xiluhua # date: 2017-01-15 n1=$1 if [ -z $n1 ] then n1=1 fi echo \'n1=\'$1 until test $[n1] -gt 2 do echo $n1 let \'n1++\' done
36. case (1)
#!/bin/bash # auth: xiluhua # date: 2017-01-15 while true do read -p \'please enter a num:\' n1 case $n1 in 1|2|3|4|5) echo \'u enter:\'$n1 ;; *) echo \'game over!\' break esac done
37. case (2)
#!/bin/bash # auth: xiluhua # date: 2017-01-15 while true do read -p \'please enter a num:\' n1 case $n1 in 1|2|3|4|5) echo \'u enter:\'$n1 ;; *) continue esac done
38. funtion
#!/bin/bash # auth: xiluhua # date: 2017-01-15 first(){ echo \'i am handsome!\' } first
39. function 传参
#!/bin/bash # auth: xiluhua # date: 2017-01-15 second(){ echo \'first args:\'$1 echo \'second args:\'$2 } second 1 2
40. 重定向
标准输入文件(stdin)：stdin的文件描述符为0，Unix程序默认从stdin读取数据。
标准输出文件(stdout)：stdout 的文件描述符为1，Unix程序默认向stdout输出数据。
标准错误文件(stderr)：stderr的文件描述符为2，Unix程序会向stderr流中写入错误信息。
41. 输出错误重定向
xiluhua@localhost ~/t2scripts $ cat echo 2>>err.log xiluhua@localhost ~/t2scripts $ less err.log cat: echo: No such file or directory
42. 2&>1
find /etc -name passwd 2>&1 | less > e.log
43. 将标准输出重定向到一个文件的同时并在屏幕上显示
格式：<command> 2>&1 | tee <logfile> xiluhua@localhost ~/t2scripts $ id das 2>&1 |tee logfile id: das: No such user xiluhua@localhost ~/t2scripts $ less logfile id: das: No such user logfile (END)
44. Here Document
xiluhua@localhost ~/t2scripts $ wc -l << EOF > 1 > 2 > 3 > EOF 3
45. function 引用
#!/bin/bash # auth: xiluhua # date: 2017-01-15 . ./t21.sh second 3 4
46. 为变量设定默认值
[ -z "$name" ] && name="obama"
47. 测试脚本语法
bash -n scripts.sh
48. 1加到100
#!/bin/bash # auth: xiluhua # date: 2017-03-19 declare -i sum=0 for i in {1..100};do sum=$[$sum+$i] if [ $i -eq 100 ];then echo $sum fi done