'''
要求：bash for循环打印下面这句话中字母数大于6的单词(昆仑万维面试题)。
shell思路：
1. 脚本创建变量存放内容或脚本传参
2. 处理下数据,把数据里面的特殊符号替换为空格.
3. 循环+判断.
4. 满足条件则输出
length() awk函数用于统计某一列或整行的字符数量
${#var}
'''

# 1.使用${#变量}
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# cat check_str.sh 
#!/bin/bash
##############################################################
# File Name:check_str.sh
# Version:V1.0
# Author:xk
# Organization: none
# Desc:
##############################################################

#1. 脚本创建变量存放内容或脚本传参
str0="We are the successors of socialism."

#2. 处理下数据,把数据里面的特殊符号替换为空格.
str=${str0/./ }

# 3. 循环+判断.
for i in $str
do
    # 4. 满足条件则输出
    if [ ${#i} -ge 6 ];then
        echo $i "长度大于6，为：" ${#i}
    fi
done

[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# bash check_str.sh 
successors 长度大于6，为： 10
socialism 长度大于6，为： 9

# 使用awk
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo "We are the successors of socialism." |xargs -n1 |awk -F"[ .]" 'length($1)>=6'
successors
socialism.
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo "We are the successors of socialism." |xargs -n1 |awk -F '[ .]' '{print$1}'
We
are
the
successors
of
socialism
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo "We are the successors of socialism." |xargs -n1 |awk -F '[ .]' '{print$1}' | awk 'length($1)>=6'
successors
socialism
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo "We are the successors of socialism." |xargs -n1 |awk -F '[ .]' '{print$1}' | awk 'length($1)>=6 {print $1}'
successors
socialism
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 

'''
在 awk 命令行中，-v RS= 选项用于设置输入记录分隔符（Record Separator, RS）为空字符串。这通常用于处理多行文本记录，
其中记录之间没有明显的分隔符（如换行符）。当 RS 被设置为空字符串时，awk 会将连续的空白行视为记录分隔符，或者更准确地说，
它会将任意长度的空白行序列视为单个记录分隔符。

在Linux中，xargs命令是一个非常强大的工具，用于从标准输入（stdin）构建并执行命令。xargs读取来自标准输入的数据，
然后将这些数据作为参数传递给指定的命令。-n1选项是xargs命令的一个重要选项，它告诉xargs每次只从输入中读取一个项目（即一个参数），
并将这个参数传递给指定的命令。
'''
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo "We are the successors of socialism." | awk -vRS=" " 'length()>=6'
successors
socialism.
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 

 # :-
# 空值或者未创建该变量
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo $name  

[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo ${name:-xiaohong}
xiaohong
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo $name

[root@Kylin-V10-sp3 /server/scripts/shell-pro]# name=xiao
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo ${name:-xiaohong}
xiao
[root@Kylin-V10-sp3 /server/scripts/shell-pro]#

# :=
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo $name1

[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo ${name1:=xiaohong}
xiaohong
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo $name1
xiaohong
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# name1=xiaohua
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo $name1
xiaohua
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 

# :+
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo $name3
xiaobai1
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo ${name3:+xiaobai}
xiaobai
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo $name3
xiaobai1
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 

 #1. % 生成指定范围的随机数.
#随机的数字（n)对一个数字取余可以得到0到n-1范围的随机数。
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo $RANDOM%5 |bc
3
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo $RANDOM%5 |bc
4
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# echo $RANDOM%5
31826%5

# 2. &&
# 检查目录是否存在
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# ls /etc/ >/dev/null 2>&1 && echo "目录存在"
目录存在

# 3. ||
# 没有则创建
root@Kylin-V10-sp3 /server/scripts/shell-pro]# tree -L 1 /root/
/root/
├── 1.py
├── 1.sh
├── anaconda-ks.cfg
├── app
├── app2
├── awkprof.out
├── conf_2024-09-11_3.tar.gz
├── hosts
├── http-dns.pcap
├── initial-setup-ks.cfg
└── test

3 directories, 8 files
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# ls /etc/abc/ >/dev/null 2>&1 || mkdir -p /root/abc/
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# tree -L 1 /root/
/root/
├── 1.py
├── 1.sh
├── abc
├── anaconda-ks.cfg
├── app
├── app2
├── awkprof.out
├── conf_2024-09-11_3.tar.gz
├── hosts
├── http-dns.pcap
├── initial-setup-ks.cfg
└── test

4 directories, 8 files
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 

 # 1. 脚本传入参数

#!/bin/bash
##############################################################
# File Name:num_calc_param_awk.sh
# Version:V1.0
# Author:xk
# Organization: none
# Desc:
##############################################################

#vars
num1=$1
num2=$2

#判断为整数
n1=`[[ $num1 =~ ^[0-9]+$ ]] && echo 0 || echo 1`  # 0 是整数
n2=`[[ $num2 =~ ^[0-9]+$ ]] && echo 0 || echo 1`

if [ $n1 -eq 1 -o $n2 -eq 1 ];then  # -o 在[]里表示or
    echo "请输入整数"
    exit
fi


# 计算
add=`awk -vn3=$num1 -vn4=$num2 'BEGIN {print n3 + n4}'`
subtract=`awk -vn3=$num1 -vn4=$num2 'BEGIN {print n3 - n4}'`
mult=`awk -vn3=$num1 -vn4=$num2 'BEGIN {print n3 * n4}'`
if [ $num2 -eq 0 ]; then
    echo  $num2 "不能作为除数"
else
    divide=`awk -vn3=$num1 -vn4=$num2 'BEGIN {print n3 / n4}'`
fi

# 输出
cat <<EOF
$num1 + $num2 = $add 
$num1 - $num2 = $subtract
$num1 * $num2 = $mult
$num1 / $num2 = $divide
EOF
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# bash num_calc_param_awk.sh 
请输入整数
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# bash num_calc_param_awk.sh 10 20
10 + 20 = 30 
10 - 20 = -10
10 * 20 = 200
10 / 20 = 0.5
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 


# 2. 交互式传入参数
#!/bin/bash
##############################################################
# File Name:num_calc.sh
# Version:V1.0
# Author:xk
# Organization: none
# Desc:
##############################################################

# 输入
read -p "请输入需要计算的内容，如: 100 20    " num1 num2

# 检查是否为数字
n1=`[[ $num1 =~ ^[0-9]+$ ]] && echo 0 || echo 1`
n2=`[[ $num2 =~ ^[0-9]+$ ]] && echo 0 || echo 1`

if [ $n1 -eq 1 -o $n1 -eq 1 ];then  # n1 n2 只要一个不是整数就退出
    echo "请输入整数"
    exit
fi

# 计算
add=`awk -vn3=$num1 -vn4=$num2 'BEGIN {print n3 + n4}'`
subtract=`awk -vn3=$num1 -vn4=$num2 'BEGIN {print n3 - n4}'`
mult=`awk -vn3=$num1 -vn4=$num2 'BEGIN {print n3 * n4}'`
if [ $n2 -eq 0 ];then
    divide=`awk -vn3=$num1 -vn4=$num2 'BEGIN {print n3 / n4}'`
else
    echo $num2 "不能作为除数"
fi

# 输出
cat <<EOF
$num1 + $num2 = $add
$num1 - $num2 = $subtract
$num1 * $num2 = $mult
$num1 / $num2 = $divide
EOF

[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# bash num_calc_read_awk.sh 
请输入需要计算的内容，如: 100 20    100 40
100 + 40 = 10
100 - 40 = 60
100 * 40 = 4000
100 / 40 = 2.5
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 

 #!/bin/bash
##############################################################
# File Name:num_calc_read_bc.sh
# Version:V1.0
# Author:xk
# Organization: none
# Desc:
##############################################################

# 输入
read -p "请输入需要计算的内容，如: 100 20    " num1 num2

# 判端是否为整数
n1=`[[ $num1 =~ ^[0-9]+$ ]] && echo 0 || echo 1`
n2=`[[ $num2 =~ ^[0-9]+$ ]] && echo 0 || echo 1`

if [ $n1 -eq 1 -o $n2 -eq 1 ];then
    echo "请按照格式输入整数"
fi

# 计算
add=`echo $num1 + $num2 | bc -l`
subtract=`echo $num1 - $num2 | bc -l`
mult=`echo $num1*$num2 | bc -l`

if [ $num2 -eq 0 ];then
    echo $num2 "不能为除数"
else
    devide=`echo $num1 / $num2 | bc -l`
fi

# 输出
cat << EOF
$num1 + $num2 = $add
$num1 - $num2 = $subtract
$num1 * $num2 = $mult
$num1 / $num2 = $devide
EOF

[root@Kylin-V10-sp3 /server/scripts/shell-pro]# 
[root@Kylin-V10-sp3 /server/scripts/shell-pro]# bash num_calc_read_bc.sh 
请输入需要计算的内容，如: 100 20    200 10
200 + 10 = 210
200 - 10 = 190
200 * 10 = 2000
200 / 10 = 20.00000000000000000000
[root@Kylin-V10-sp3 /server/scripts/shell-pro]#