shell的灵活运用 （函数，关联数组，循环，awk，sed等）

题目

提示：没有基础请先看看基础部分的讲解，否则看不懂

1，编写函数，实现判断是否无位置参数，如无参数，提示错误

代码：

#bash/bin
function a() {b=$#   #判断传入的参数个数
#       echo $bif [ $b -eq 0 ]   # 看参数个数是不是等于0 thenecho "no"elseecho "yes"fi
}
a

1，当不传入参数时，结果为：

no

2，当传入参数时，结果为：

yes

2，编写函数实现两个数字做为参数，返回最大值

代码

function a() {    # 定义函数num1=$1   # 获取第一个参数
#       echo "num1:$num1"num2=$2
#       echo "num2:$num2"if [ $num1 -gt $num2 ]     # 2个参数进行比较thenecho "$num1"    # 返回第一个参数elseecho "$num2"   # 返回得第二个参数fi
}
c=$(a 200 300)     # 传入2个参数，并且将返回值赋值给c
echo "the $c is more big"

运行输出结果：

[root@localhost ~]# bash functiontest.sh 
the num1:200
num2:300
300 is more big

3，编写函数，实现两个整数位参数，计算加减乘除

代码

a(){one=$1two=$2echo  "$one + $two = `expr $one + $two`"echo  "$one - $two = `expr $one - $two`"echo  "$one * $two = `expr $one \* $two`"echo  "$one / $two = `expr $one / $two`"printf  "$one / $two = `expr $one / $two`\n"}
a 2 3

运行结果

[root@localhost ~]# bash functiontest.sh 
2 + 3 = 5
2 - 3 = -1
2 * 3 = 6
2 / 3 = 0
2 / 3 = 0

4、将/etc/shadow文件的每一行作为元数赋值给数组

代码

function a(){a=`wc -l /etc/shadow | cut -d" " -f1`   # 将目标文件进行剪切，提取需要的数据，这里代表数据个数
for i in `seq $a`
dob=`expr $i - 1`     # 数组下标arr[$b]=`awk 'NR=='$i'{print}' /etc/shadow`    # 将对应的哪一行数据放入到数组
done
}
a
echo ${arr[0]}     # 打印数组的第一个元素
echo ${arr[1]}    #第二个
echo ${arr[2]}
echo ${arr[3]}

以上的结果显示为: 结果的验证可以用cat 命令对目标文件进行对比

[root@localhost ~]# bash functiontest.sh 
root:$6$SqQF33Q5poRxzqNJ$mAZ7EJuymCGVS6HxSAinq4danhF48kUbkyg/Kck3VJ8mIO5tDJlrsbQ04.aXbUb63rif82rIR/Xuatvcdj6Bp1::0:99999:7:::
bin:*:19121:0:99999:7:::
daemon:*:19121:0:99999:7:::
adm:*:19121:0:99999:7:::

5，使用关联数组统计文件/etc/passwd中各个用户的shell类型

代码

function a(){read -p "which user's shell type that you want find?:" shell_type  # 提示加读取输入的变量declare -A arry    # 必须声明关联数组l=`wc -l /etc/passwd | cut -d " " -f1`   # 计算数据的条数for i in `seq $l`do
#               ass-arry[`expr $i - 0`] index=`cat /etc/passwd | awk 'BEGIN{FS=":"}{print $1}' | awk  'NR=='$i'{print}'`  # 关联数组的下标#       echo "index $index"declare -A arryarry["$index"]=`cat /etc/passwd | awk 'BEGIN{FS=":"}{print $7}' | awk 'NR=='$i'{print}'`  # 关联数组的值doneecho "the user $shell_type's shell type is ${arry[$shell_type]}"   # 格式化输出
}
a

运行的结果：

[root@localhost ~]# bash functiontest.sh 
which user's shell type that you want find?:fu
the user fu's shell type is /bin/bash[root@localhost ~]# bash functiontest.sh 
which user's shell type that you want find?:root
the user root's shell type is /bin/bash[root@localhost ~]# bash functiontest.sh 
which user's shell type that you want find?:bin
the user bin's shell type is /sbin/nologin

6，使用关联数组按扩展名统计指定目录中文件的数量

代码

function a() {read -p "input a file path (absolute):(such as input /etc/)>" path  # 输入路径read -p "which type of file are you count ?:(such as input txt or sh ...)>" type1  # 输入文件类型a=`ls -l $path | awk '{print $9}' | grep '^[^$]' | awk 'BEGIN{FS="."}{print $2}'`   # 看有几个文件有后缀名declare -A arrfor i in $ado#         echo "file type: $i"arr["$i"]=`expr ${arr["$i"]} + 1`   # 对文件类型计数表示该类型文件个数doneecho "the file of type $type1 have ${arr[$type1]}"
}
a

运行结果如下：结果的验证可以用自己数

[root@localhost ~]# bash functiontest.sh 
input a file path (absolute):(such as input /etc/)>/etc/
which type of file are you count ?:(such as input txt or sh ...)>conf
the file of type conf have 36[root@localhost ~]# bash functiontest.sh 
input a file path (absolute):(such as input /etc/)>/etc/
which type of file are you count ?:(such as input txt or sh ...)>d
the file of type d have 24

7，编写函数 ，判断是否有参数，存在为Ok，不存在为FAILED，要求绿色OK和红色FAILED

代码：

function a() {b=$#
##      echo $bif [ $b -eq 0 ]thenecho -e "\e[31m failde \e[0m";elseecho -e "\e[32m ok \e[0m";fi
}
a 1