- 编写简单的hello world脚本，查看脚本内容，并运行
使用bash命令运行shell脚本
[lwj@192 file01]$ touch test.sh //创建新文件
[lwj@192 file01]$ vim test.sh //编辑文件内容
[lwj@192 file01]$ cat test.sh //查看文件内容
#!/bin/bash
echo "Hello World!"
[lwj@192 file01]$ bash test.sh //运行shell脚本
Hello World!- 使用declare进行运算，declare命令仅支持整数的数值运算，使用一段代码进行比较运算
[lwj@192 file01]$ declare -i var=10+10 //加法
[lwj@192 file01]$ echo $var
20
[lwj@192 file01]$ declare -i var=10*10 //乘法
[lwj@192 file01]$ echo $var
100
[lwj@192 file01]$ declare -i var=20-10 //减法
[lwj@192 file01]$ echo $var
10
[lwj@192 file01]$ declare -i var=10/3 //取整
[lwj@192 file01]$ echo $var
3
[lwj@192 file01]$ vim test.sh //编辑文件
[lwj@192 file01]$ cat -n test.sh //查看文件
1 #!/bin/bash
2 if [ $# -ne 2 ];then
3 echo "Usage: $0 number1 number2"
4 exit 1
5 fi
6 number1="$1"
7 number2="$2"
8 if (( number1>number2 ));then
9 echo "$number1 > $number2"
10 elif (( number1 < number2 ));then
11 echo "$number1 < $number2"
12 elif (( number1 == number2 ));then
13 echo "$number1 == $number2"
14 else
15 echo "should never be here."
16 fi
[lwj@192 file01]$ bash test.sh 1 2 //1和2比较
1 < 2
[lwj@192 file01]$ bash test.sh 2 1 //2和1比较
2 > 1
[lwj@192 file01]$ bash test.sh 2 2 //2和2比较
2 == 2- 使用test命令对两个数值比较（等于、小于、大于等于）
[lwj@192 file01]$ vim myscript.sh
[lwj@192 file01]$ cat myscript.sh
#!/bin/bash
a=11;b=16
test $a -eq $b && echo "$a = $b" || echo "$a != $b" //等于
test $a -gt $b && echo "$a < $b" || echo "$a >= $b" //小于
test $a -ge $b && echo "$a >= $b" || echo "$a < $b" //大于等于
[lwj@192 file01]$ sh myscript.sh
11 != 16
11 >= 16
11 < 16- 使用test命令对两个字符串比较（等于、非空），test字符串运算
[lwj@192 file01]$ vim myscript.sh
[lwj@192 file01]$ cat myscript.sh
#!/bin/bash
a="centos"
test -z "$a" && echo "'$a' is null" || echo "'$a' is not null" // 非空
test "$a" == "centos" && echo "'$a'='centos'" || echo "'$a'!='centos'" //等于
[lwj@192 file01]$ sh myscript.sh
'centos' is not null // 非空
'centos'='centos' //等于- 使用test命令进行布尔运算,注释说明含义 -a:当表达式$a和$b同时为真时复合表达式返回真，否则为假
-o:当表达式$a和$b任意一个表达式为真时复合表达式返回真，否则为假
[lwj@192 file01]$ vim myscript.sh
[lwj@192 file01]$ cat myscript.sh
#!/bin/bash
a=11;b=16
f1="myscript.sh"
f2="file2"
test $b -o $a && echo "$a >= $b" || echo "$a < $b"
test -e "$f1" -a -r "$f1" && echo "$f1 is readable" || echo "$f1 is not exist or not readable"
[lwj@192 file01]$ sh myscript.sh
11 >= 16
myscript.sh is readable- 使用[] 对文件类型、文件权限、文件比较等进行练习。 文件类型-f:当文件fname的文件类型为普通文件时返回真，否则为假
文件权限-r:当文件fname存在具有可读权限时返回真，否则为假
文件比较-nt:当文件fname1比文件fname2新时返回真，否则为假
[lwj@192 file01]$ vim myscript.sh
[lwj@192 file01]$ cat myscript.sh
#!/bin/bash
f1="myscript.sh"
f2="file2"
[ -f "$f1" ] && echo "$f1:ordinary file" || echo "$f1:not ordinary file"
[ -r "$f1" ] && echo "$f1:readable" || echo "$f1: not readable"
[ "$f1" -nt "$f2" ] && echo "$f1 is newer than $f2" || echo "$f2 is newer than $f1"
[lwj@192 file01]$ sh myscript.sh
myscript.sh:ordinary file
myscript.sh:readable
myscript.sh is newer than file2- 使用if-elif结构完成功能。猜数字游戏
[lwj@192 file01]$ vim myscript.sh
[lwj@192 file01]$ cat -n myscript.sh
1 #!/bin/bash
2 a=0
3 b=99
4 random_num=$(( $RANDOM*100/32767 ))
5 read -p "请输入竞猜数字:" guess_num
6 while [ $random_num -ne $guess_num ]
7 do
8 if [ $random_num -gt $guess_num ]; then
9 echo "猜小了,范围变为 "$guess_num"-"$b",请输入竞猜数字:"
10 a=$guess_num
11 read guess_num
12 elif [ $random_num -lt $guess_num ]; then
13 echo "猜大了,范围变为 "$a"-"$guess_num",请输入竞猜数字:"
14 b=$guess_num
15 read guess_num
16 else
17 echo "请输入0-99的数字"
18 fi
19 done
20 echo "恭喜，竞猜正确"
[lwj@192 file01]$ sh myscript.sh
请输入竞猜数字:50
猜大了,范围变为 0-50,请输入竞猜数字:
25
猜大了,范围变为 0-25,请输入竞猜数字:
13
猜大了,范围变为 0-13,请输入竞猜数字:
7
猜大了,范围变为 0-7,请输入竞猜数字:
4
猜大了,范围变为 0-4,请输入竞猜数字:
2
猜大了,范围变为 0-2,请输入竞猜数字:
1
猜大了,范围变为 0-1,请输入竞猜数字:
0
恭喜，竞猜正确- 结合case-in和函数，完成简易计算器。（选择运算符，再输入数）
[lwj@192 file01]$ vim mytest.sh
[lwj@192 file01]$ cat -n mytest.sh
1 #!/bin/bash
2 y=y
3 while [ "$y" === "y" ] || [ "$y" == "Y" ]
4 do
5 read -p "please input the first num:" num1
6 read -p "please input the operator:" a
7 read -p "please input the second num:" num2
8 case "$a" in
9 +)
10 echo "运算结果为:$(($num1+$num2))"
11 ;;
12 -)echo "运算结果为:$(($num1-$num2))"
13 ;;
14 *)echo "运算结果为:$((%num1*$num2))"
15 ;;
16 /)echo "运算结果为:$(($num1/$num2))"
17 ;;
18 esac
19 read -p "是否还要继续运算(y/n):" y
20 done
[lwj@192 file01]$ sh mytest.sh
please input the first num:9
please input the operator:-
please input the second num:2
运算结果为 ：7
是否还要将继续运算（y/n）：y
please input the first num:3
please input the operator:+
please input the second num:2
运算结果为 ：5
是否还要将继续运算（y/n）：y
please input the first num:3
please input the operator:*
please input the second num:3
运算结果为 ：9
是否还要将继续运算（y/n）：n- 对函数传递参数大于、等于、小于所需参数的三种情形分别试验
[lwj@192 file01]$ vim myhs.sh
[lwj@192 file01]$ cat -n myhs.sh
1 #!/bin/bash
2 function sum()
3 {
4 echo 'input paramenters are:$@ = "'$@'"'
5 if (test $# -lt 2);then
6 echo "传递的参数小于指定参数个数"
7 return 1
8 elif (test $# -gt 2);then
9 echo "传递的参数大于指定参数个数"
10 return 1
11 fi
12 echo "传递的参数等于指定参数个数"
13 echo "var_sum=$(($1+$2))"
14 }
15 sum 1
16 sum 1 2
17 sum 1 2 3
[lwj@192 file01]$ sh myhs.sh
input paramenters are:$@ = "1"
传递的参数小于指定参数个数
input paramenters are:$@ = "1 2"
传递的参数等于指定参数个数
var_sum=3
input paramenters are:$@ = "1 2 3"
传递的参数大于指定参数个数本文章为转载内容，我们尊重原作者对文章享有的著作权。如有内容错误或侵权问题，欢迎原作者联系我们进行内容更正或删除文章。
