比较两个数大小


#/bin/bash

echo "please enter two number"

read a

read b

if [ $a -eq $b ]

then echo "$a = $b"

elif test [ $a -gt $b ]

then echo "$a > $b"

else echo "$a < $b"

fi



查找/root/目录下是否存在该文件


#/bin/bash

echo "enter a file name:"

read a

if [ -e /root/$a ]

then echo "the file is exist!"

else echo "the file is not exist!"

fi


for循环应用

#/bin/bash

clear

for num in 1 2 3 4 5 6 7 8 9 10

do

echo "$num"

done


判断用户是否登录


#/bin/bash

echo "Please enter a user:"

read a

b=$(whoami)

if test $a = $b

then echo "the user is running."

else echo "the user is not running."

fi



删除当前目录下大小为0的文件


#/bin/bash

for filename in `ls`

do

if test -d $filename

then b=0

else

a=$(ls -l $filename | awk '{ print $5 }')

if test $a -eq 0

then rm $filename

fi

fi

done



创建文件夹


#/bin/bash

while :

do

echo "please input file's name:"

read a

if test -e /root/$a

then

echo "the file is existing Please input new file name:"

else

mkdir /root/$a

echo "you aye sussesful!"

break

fi

done





查找最大文件


#/bin/bash

a=0

for name in *.*

do

b=$(ls -l $name | awk '{print $5}')

if test $b -ge $a

then a=$b

namemax=$name

fi

done

echo "the max file is $namemax"




case语句练习


#!/bin/bash

clear

echo "enter a number from 1 to 5:"

read num

case $num in

1) echo "you enter 1"

;;

2) echo "you enter 2"

;;

3) echo "you enter 3"

;;

4) echo "you enter 4"

;;

5) echo "you enter 5"

;;

*) echo "error"

;;

esac



内置命令的使用(可以做开机提示语)


#/bin/bash


clear

echo "Hello, $USER"

echo

echo "Today 's date is `date`"

echo

echo "the user is: `who`"

echo

echo "this is `uname -s`"

echo

echo "that's all folks! "

echo "dir root "

ls -la /root



OR


#/bin/bash


clear

echo "Hello, $USER"

echo

echo "Today 's date is `date`"

echo

echo "the user is: "

who

echo

echo "this is `uname -s`"

echo

echo "that's all folks! "