shell脚本入门

Shell 脚本快速入门

#!/bin/bash

//变量的赋值，=前后不能有空格，访问用$

myTest="hello world"

myNum=30

yourNum=40

//shell四则运算符号前后有空格，乘法需转义

//其他运算符，=、==、！=、！、-o、-a

val=`expr $myNum + $yourNum`

echo $val

val=`expr $myNum \* $yourNum`

echo "$val"

val=`expr $myNum / $yourNum`

echo "$val"

echo ${#myTest}   #字符串长度

echo ${myTest:1:4}   #字符串切片

 

array=(1 2 3 4 5)

array2=(aa bb cc dd ee)

value=${array[3]}

echo $value

value2=${array2[3]}   #数组取值

echo $value2

length=${#array[*]}    #数组长度

echo $length

 

echo "hello world"

echo helo world

text="hello world"

echo $text

 

echo -e "hello \nworld"

 

echo "hello world" > a.txt

 

echo `date`    #当前系统时间

 

printf "%-10s %-8s %-4s\n" 姓名 性别 体重kg 

printf "%-10s %-8s %-4.2f\n" 郭靖 男 66.1234

printf "%-10s %-8s %-4.2f\n" 杨过 男 48.6543

printf "%-10s %-8s %-4.2f\n" 郭芙 女 47.9876

 

test $[myNum] -eq $[yourNum]

test myNum=yourNum

# for 循环，

for i in {1..5}  # 也可以用  for I in 5 6 7 8 9

do

    echo $i + "  eek"

done

 

for FILE in /etc/p*

do

    echo $FILE

done

 

COUNTER=0

#while 循环

while [ $COUNTER -lt 5 ]

do

        COUNTER=`expr $COUNTER + 1`

        echo $COUNTER

done

echo 'input...'

while read FILM

do

                  # if then else elif  使用  [] 并且 [  ] 两边都有空格

        if [ $FILM == "exit" ]

        then

                                   #跳出循环

                break

        else

                echo "great $FILM"

        fi

done

 

#函数

sysout(){

        echo "hello world sysout"

}

sysout

 

calc(){

        anum=$1   #接受第一个参数

        echo $anum

        bnum=$2

        echo $bnum

        echo $#      $接收参数个数

        echo $*       $打印所有的参数

        return $(($anum + $bnum))

}

calc 44 55

result1=$?

echo $result1

$echo result1 > a.txt

echo input < /etc/passwd