linux运维实战练习-2015年9月13日-9月15日课程作业

1、描述shell程序的运行原理;

    shell既是命令语言、程序设计语言也是命令解释程序。

    shell脚本通常是以#!起始的文本文件,如“#!/bin/bash”,这行被称为shebang,指定了解释此脚本shell的路径,执行脚本时系统会调用这个shell来运行此脚本。字符#指明注释的开始。注释部分以#为起始,一直延续到行尾,注释行通常用于为代码提供注释信息,或者用于暂停执行某行代码,会被解释器忽略。

     shell脚本是把命令堆砌在一起,shell通过词法分析,语法分析,语义分析,按顺序、选择或循环执行脚本中的命令。脚本运行结束,此shell进程也即终止

2、总结shell编程中所涉及到的所有知识点(如:变量、语法、命令状态等等等,要带图的哟);

      变量、变量运算及条件测试

      条件判断语句if、case及read命令

      循环语句for,while,until

      函数、死循环、模块话编程

3、总结课程所讲的所有循环语句、条件判断的使用方法及其相关示例;(if (jpg|png is not exist);echo ”You say a XX“)

      循环语句for,while,until

      变量、变量运算及条件测试

4、写一个脚本:如果某路径不存在,则将其创建为目录;否则显示其存在,并显示内容类型;(不要怀疑,就是这么简单)

[root@liaodijin ~]# cat test.sh

#!/bin/bash

#

read -t 10 -p "Please input a file path: " path

if [ -z "$path" ];then

   echo -e "\n\033[31mError:\033[0mplease input a file path"

   exit 1

  elif [ ! -e "$path" ];then

     mkdir -p $path $>/dev/null

     echo "your input $path is not exist"

elif [ -f "$path" ];then

     echo  "$path is a general file"

     echo -e "\033[31mThe $path:\033[0m"

     cat $path

elif [ -d "$path" ];then

     echo "$path is a directory"

     echo -e "\033[31mThe $path:\033[0m"

     ls $path

else echo "$path unknown type"

fi

 

测试结果:

[root@liaodijin ~]# bash test.sh

Please input a file path: /etc/fstab

/etc/fstab is a general file

The /etc/fstab:

 

#

# /etc/fstab

# Created by anaconda on Thu Sun 19 22:48:50 2015

#

# Accessible filesystems, by reference, are maintained under '/dev/disk'

# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info

#

/dev/mapper/VolGroup-lv_root /                       ext4    defaults        1 1

UUID=46c42e9f-f101-4209-9590-afa295415eaf /boot                   ext4    defaults        1 2

/dev/mapper/VolGroup-lv_data /data                   ext4    defaults        1 2

/dev/mapper/VolGroup-lv_swap swap                    swap    defaults        0 0

tmpfs                   /dev/shm                tmpfs   defaults        0 0

devpts                  /dev/pts                devpts  gid=5,mode=620  0 0

sysfs                   /sys                    sysfs   defaults        0 0

proc                    /proc                   proc    defaults        0 0

[root@liaodijin ~]# bash test.sh

Please input a file path: /tmp

/tmp is a directory

The /tmp:

ks-script-utpPS_      yum.log

ks-script-utpPS_.log  yum_save_tx-2015-09-15-20-24RcJDyn.yumtx

shell                 yum_save_tx-2015-09-16-20-29ihcHuJ.yumtx

test.sh              yum_save_tx-2015-09-16-20-30ZOEQ7w.yumtx

test.sh               yum_save_tx-2015-09-16-20-32anadvE.yumtx

[root@liaodijin ~]# bash test.sh

Please input a file path: xx

your input xx is not exist

[root@liaodijin ~]# ls

~                cc                  shell          test3.sh       xx

$                init.sh             test1.sh       test3.sh.orig

aa               install.log         test1.sh.orig  test.sh

anaconda-ks.cfg  install.log.syslog  test.sh       test.sh.orig

bb               qq                  test.sh.orig  trash.sh

[root@liaodijin ~]# bash test.sh

Please input a file path: /dev/null

/dev/null unknown type

[root@liaodijin ~]# bash test.sh

Please input a file path: 

Error:please input a file path

[root@liaodijin ~]# bash test.sh

Please input a file path: aa bb cc

your input aa bb cc is not exist

5、写一个脚本完成如下功能:判断给定的两个数值,哪个大哪个小,给定数值的方法:脚本参数,命令交互(使用read,依然如此简单)

[root@test shell]# cat 6.sh

#!/bin/bash                                 

#

error(){

cat<<EOF

+--------------------------------------------------------+

| Function of the script is to compare two numbers size |    

| Instructions:num_compare.sh num1 num2                  |

| Example:num_compare.sh 11 22                           | 

+--------------------------------------------------------+

EOF

}

echo "$*"|grep '[[:alpha:]]' &>/dev/null && error && exit 1

if [ $# -gt 2 -o $# -le 1 ];then

error

exit 2

elif [ "$1" -gt "$2" ];then

     echo -e "The max is $1\nThe min is $2"

elif [ "$1" -lt "$2" ];then

     echo -e "The max is $2\nThe min is $1"

elif [ "$1" -eq "$2" ];then

     echo "$1 and $2 as large as"

else error

fi

 

测试结果如下:

[root@test shell]# bash 6.sh

+--------------------------------------------------------+

| Function of the script is to compare two numbers size |    

| Instructions:num_compare.sh num1 num2                  |

| Example:num_compare.sh 11 22                           | 

+--------------------------------------------------------+

[root@test shell]# bash 6.sh a 1

+--------------------------------------------------------+

| Function of the script is to compare two numbers size |    

| Instructions:num_compare.sh num1 num2                  |

| Example:num_compare.sh 11 22                           | 

+--------------------------------------------------------+

[root@test shell]# bash 6.sh 1 a

+--------------------------------------------------------+

| Function of the script is to compare two numbers size |    

| Instructions:num_compare.sh num1 num2                  |

| Example:num_compare.sh 11 22                           | 

+--------------------------------------------------------+

[root@test shell]# bash 6.sh xy zx

+--------------------------------------------------------+

| Function of the script is to compare two numbers size |    

| Instructions:num_compare.sh num1 num2                  |

| Example:num_compare.sh 11 22                           | 

+--------------------------------------------------------+

[root@test shell]# bash 6.sh 12a 2b3

+--------------------------------------------------------+

| Function of the script is to compare two numbers size |    

| Instructions:num_compare.sh num1 num2                  |

| Example:num_compare.sh 11 22                           | 

+--------------------------------------------------------+

[root@test shell]# bash 6.sh 10 34

The max is 34

The min is 10

6、求100以内所有奇数之和(至少用3种方法。是的这是我们的作业^_^)

(1)、[root@liaodijin ~]# cat test4.sh

#!/bin/bash

#

y=0

for x in $(seq 1 2 100);do                  # for循环                

    y=$[$y+$x]

done

    echo "The sum is $y"

[root@liaodijin ~]# bash test4.sh

The sum is 2500

(2)、[root@liaodijin ~]# cat test5.sh

#!/bin/bash

#

x=1

while [ "$x" -le 100 ];do                  # while循环

   if [ $[$x%2] -eq 1 ];then

  let y+=$x

   fi

     let x++

done

    echo "The sum is $y"

[root@liaodijin ~]# bash test5.sh

The sum is 2500

(3)、[root@liaodijin ~]# cat test10.sh

#!/bin/bash

#

x=1

until [ $x -gt 100 ];do                    # until循环

      if [ $[$x%2] -eq 1 ];then

          let y+=$x

       fi

       let x++

done

       echo "The sum is $y"

[root@liaodijin ~]# bash test10.sh

The sum is 2500

7、写一个脚本实现如下功能:

      (1) 传递两个文本文件路径给脚本;

      (2) 显示两个文件中空白行数较多的文件及其空白行的个数;

      (3) 显示两个文件中总行数较多的文件及其总行数;

[root@liaodijin ~]# cat test6.sh

#!/bin/bash

#

read -t 10 -p "Please enter two file path: " file1 file2   #发现一个问题,这里我不输入等10S后为什么不会结束,按ENTER键也不会结束

spaceline1=$(grep "^$" $file1|wc -l)

spaceline2=$(grep "^$" $file2|wc -l)

line1=$(cat $file1|wc -l)

line2=$(cat $file2|wc -l)

###############################################################

compare(){     # 这里我们发现第2问和第3问的要求通过一个表达式只是参数不同就可以实现,所以我们这里先定义一个函数,调用2次就可以实现,省得重复写命令

 

if [ $a -gt $b ];then

     echo -e " max $file1\n $file1 :$a"

elif [ $a -lt $b ];then

     echo -e "max $file2\n $file2 :$b"

elif [ $a -eq $b ];then

     echo -e "$file1 and $file2 as large as\n space line is $a"

else echo "Error please enter two file path!"

fi

}

 

 

 

##############################################################

a=$spaceline1

b=$spaceline2

echo "The space_line:"

compare

echo

a=$line1

b=$line2

echo "The line:"

compare

 

测试结果:

[root@liaodijin ~]# bash test6.sh

Please enter two file path: /root/aa /root/bb

The space_line:

 max /root/aa

 /root/aa :2

 

The line:

max /root/bb

 /root/bb :11

[root@liaodijin ~]# cat aa

aaaaaaaaaaaaaaaaaa

 

aaaaaaaaaaaaaa

 

aaaaaaaaaaaaaaaaaaa

[root@liaodijin ~]# cat bb

bbbbbbbbbbbb

bbbbbbbbb

a

b

c

ccc

cccc

d

 

d

c

8、写一个脚本

(1) 提示用户输入一个字符串;

(2) 判断:

如果输入的是quit,则退出脚本;

否则,(继续等待用户输入并)显示其输入的字符串内容;


[root@liaodijin ~]# cat test8.sh

#!/bin/bash

#

read -t 10 -p "Please enter string: " var

case $var in

quit)

    exit 1

     ;;

*)

     echo "$var"

     ;;

esac

 

测试结果:

[root@liaodijin ~]# bash test8.sh

Please enter string: 

[root@liaodijin ~]# bash test8.sh

Please enter string: nihaodaf

nihaodaf

[root@liaodijin ~]# bash test8.sh

Please enter string: quit

2、

[root@test shell]# cat 9.sh

#!/bin/bash

#

while true;do

read -p "Please enter string: " str

[ $str == quit ]&&break

echo $str

done

 

测试结果:

[root@test shell]# bash 9.sh

Please enter string: nihao

nihao

Please enter string: sb

sb

Please enter string: quit


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