shell之常用的一些命令2

前言

  自我感觉学习shell要常用`man`,`--help`这样挺方便去写的，光靠熟练远远不够的

?

#!/bin/bash

wget命令

我用到最多就是请求http网站啦，一般很少加参数

set -x

url(){

timeout=6

fail=0

success=0

while true

do

        wget --timeout=$timeout --tries=1 https://www.cnblogs.com/zqxFly/ -q -o /dev/null

        if [ $? -ne 0]

    then

            let fail=fail+1

        else

                let success+=1

        fi

        if [ $success -ge 1]

    then

                echo success

                exit 0

        fi

        if [ $fails -ge 2]

    then

                ttry="sys is dowm"

                echo $ttry|tee|mail -s "https://www.cnblogs.com/xxx"

                exit 2

        fi

done

}

url

 

wget 接http link

 

expr 命令是一个手工命令行计数器

1.结合match进行整数判断

if [[`expr match "$1" "[0-9] [0-9]*$"` == 0 ] ]

then

echo "$1 is not a num"

else

echo "$1 is a num"

fi

2.判断字符

expr $1 + 1 >/dev/null 2>&1

[ $? -eq 0 ] &&echo int || echo chars

while true

do

    read -p "hello adol":a

    expr $a + 0 >/dev/null 2>&1

    [ $? -eq 0 ] && echo int || echo chars

done

3.整数运算[ $# -ne 2 ] &&{

echo $"usage $0 num1 num2"

exit 1

}

a=$1

b=$2

expr $a + $b + 110 &>/dev/null

if [ $? -ne 0 ]

then

    echo "you must two nums"

    exit

fi

echo "a-b=$(($a-$b))"

echo "a+b=$(($a+$b))"

echo "a*b=$(($a*$b))"

echo "a/b=$(($a/$b))"

echo "a**b=$(($a**$b))"

echo "a%b=$(($a%$b))"

 

bc 命令是任意精度计算器语言

bc(选项)(参数)

通过管道符

echo "1.11+2" | bc

直接输入bc

 

read命令用于从标准输入读取数值