#!/bin/bash

echo "Hi, what your name?"
read name
echo "wow, you are $name"

name="luoxn28" #变量名和等号之间不能有空格，这个和熟悉的语言不同
echo $name   #使用变量
echo ${name} #使用变量，使用{}为了标识变量的边界

name="luoxn28-2" #重新定义了变量name
readonly name="luoxn28" #只读变量
unset name #删除变量name

#!/bin/bash
echo "File Name: $0"
echo "First Parameter : $1"
echo "First Parameter : $2"
echo "Quoted Values: [email protected]"
echo "Quoted Values: $*"
echo "Total Number of Parameters : $#"

#!/bin/bash
echo "\$*=" $*
echo "\"\$*\"" "$*"

echo "\[email protected]" [email protected]
echo "\"\[email protected]\"" "[email protected]"

echo "print echo param from \$*"
for var in $*
do
        echo $var
done

echo "print echo param from \[email protected]"
for var in [email protected]
do
        echo $var
done

echo "print echo param from \"\$*\""
for var in "$*"
do
        echo $var
done

echo "print echo param from \"\[email protected]\""
for var in "[email protected]"
do
        echo $var
done

#!/bin/bash
DATE=`date`
echo "Date is $DATE"
USERS=`who | wc -l` # wc -l 统计行数，也就是统计当前有多少个用户在线
echo "Logged in user are $USERS"
UP=`date ; uptime` #显示系统的一些信息
echo "Uptime is $UP"

#!/bin/bash
a=1
b=2

var=`expr $a + $b`
echo "a - b: $var"
var=`expr $a - $b`
echo "a + b: $var"
var=`expr $a \* $b` # *前必须加\
echo "a * b: $var"
var=`expr $a / $b`
echo "a / b: $var"
   
if [ $a == $b ] # []与参数之间必须有一个空格
then    
    echo "a equal b"
fi      

if [ $a != $b ] 
then    
    echo "a not equal b"
fi

#!/bin/bash

a=1
b=2
if [ $a -eq $b ]
then
   echo "$a -eq $b : a is equal to b"
else
   echo "$a -eq $b: a is not equal to b"
fi
if [ $a -ne $b ]
then
   echo "$a -ne $b: a is not equal to b"
else
   echo "$a -ne $b : a is equal to b"
fi
if [ $a -gt $b ]
then
   echo "$a -gt $b: a is greater than b"
else
   echo "$a -gt $b: a is not greater than b"
fi
if [ $a -lt $b ]
then
   echo "$a -lt $b: a is less than b"
else
   echo "$a -lt $b: a is not less than b"
fi
if [ $a -ge $b ]
then
   echo "$a -ge $b: a is greater or  equal to b"
else
   echo "$a -ge $b: a is not greater or equal to b"
fi
if [ $a -le $b ]
then
   echo "$a -le $b: a is less or  equal to b"
else
   echo "$a -le $b: a is not less or equal to b"
fi

#!/bin/bash

file="./subHello.sh"

if [ -e $file ]
then
    result=`sh $file`
    echo "$result"
else
    echo "not find $file"
fi

printf "hello world"
printf "hi %s" "luoxn28"
printf "name: %s, age: %d" "luoxn28", 23
# 格式只指定了一个参数，但多出的参数仍然会按照该格式输出，format-string 被重用
printf "%s" "arg1" "arg2"

if [ xxx ]
then
    xxx
elif [ xxx ]
then
    xxx
fi  

for var in xxx
do
    echo "var: $var"
done 

#!/bin/bash
for file in $HOME/.bash*
do
    echo $file
done 

#!/bin/bash
var=0
while [ $var -lt 5 ]
do
    var=`expr $var + 1` # 注意，运算符前后有空格
    echo $var
done

#!/bin/bash
function hello() {
        echo "hello world"
}

hello

#!/bin/bash

shellName="$0"
echo $shellName # 打印shell脚本名称

os="null"
case "`uname`" in 
    Linux*) os="Linux"
esac
echo $os # 打印系统名称

nginx=$(ps -ef | grep nginx | grep -v grep) # grep -v grep是为了排除grep自身查找
#echo $nginx
if [ -n "$nginx" ] # 如果$nginx字符串长度大于0
then
    echo "nginx is running..."
else
    echo "nginx not running..., start it now"
    /nginx/sbin/nginx # 启动nginx，nginx安装目录为/nginx
fi