Linux入门之——shell语言基础
shell脚本由shell命令组成文本文件输出语句的使用echo1.普通输出[root@localhost ~]# echo linuxlinux[root@localhost ~]# echo "help word"help word[root@localhost ~]# echo -e "shell \n python"shellpython[root@localhost ~]# echo -
·
shell脚本
由shell命令组成文本文件
输出语句的使用
echo
1.普通输出
[root@localhost ~]# echo linux
linux
[root@localhost ~]# echo "help word"
help word
[root@localhost ~]# echo -e "shell \n python"
shell
python
[root@localhost ~]# echo -e "shell\npython"
shell
python
[root@localhost ~]# echo -e "shell\tpython"
shell python
[root@localhost ~]#
2.“”与‘’的区别
[root@localhost ~]# echo "oooo!!"
echo "ooooecho 'oooo!!'"
ooooecho 'oooo!!'
[root@localhost ~]#
引号的使用：
| 格式 | 作用 |
|---|---|
| 单引号 | 所有字符会被作为普通字符输出 |
| 双引号 | 特殊字符会被转义 |
”“表示重复执行历史命令的最后一行
输出多行内容 （here document ）
cat
cat << 【开始符号】。。。【结束符号】
[root@localhost ~]# cat << eof
> linux
> python
> shell
> C++
> java
> eof
linux
python
shell
C++
java
[root@localhost ~]#
[root@localhost ~]# cat << ll
> hfdasj
> .shjf
> shdujf
> ll
hfdasj
.shjf
shdujf
[root@localhost ~]#
重定向符号
| 名称 | 文件 |
|---|---|
| 标准输入设备文件 | /dev/stdin |
| 标准输出设备文件 | /dev/stdout |
| 标准错误输出文件 | /dev/stderr |
输出重定向符号
| 符号 | 作用 |
|---|---|
| > | 覆盖 |
| >> | 追加 |
| 2> | 仅用于重定向标准错误 |
| &> | 输出重定向，结=杰锅不会显示屏幕上 |
[root@localhost ~]# ls | > /dev/null
[root@localhost ~]# ls > ./ttt.txt
[root@localhost ~]# cat ./ttt.txt
anaconda-ks.cfg
jiaowu.sql
mysqlbak
ttt.txt
[root@localhost ~]# ls >> ./ttt.txt
[root@localhost ~]# cat ./ttt.txt
anaconda-ks.cfg
jiaowu.sql
mysqlbak
ttt.txt
anaconda-ks.cfg
jiaowu.sql
mysqlbak
ttt.txt
输入重定向符号
[root@localhost ~]# tr 'a-z' 'A-Z' < ./ttt.txt
ANACONDA-KS.CFG
JIAOWU.SQL
MYSQLBAK
TTT.TXT
ANACONDA-KS.CFG
JIAOWU.SQL
MYSQLBAK
TTT.TXT
变量的使用
变量名称规范
只能字母、数字、下划线
只能以字母、下划线开头
见名知义
不能shell关键字冲突
调用变量的值
$变量名称
${变量名称}
[root@localhost ~]# name=djfhkjasd
[root@localhost ~]# echo $name
djfhkjasd
[root@localhost ~]# echo my name is $name
my name is djfhkjasd
[root@localhost ~]# echo "my name is ${name}"
my name is djfhkjasd
变量的数学运算
[root@localhost ~]# a=10
[root@localhost ~]# b=20
[root@localhost ~]# c=$a+$b
[root@localhost ~]# echo $c
10+20
[root@localhost ~]# c=$((a+b))
[root@localhost ~]# echo $c
30
[root@localhost ~]# c=$a+$b
[root@localhost ~]# let c=a+b
[root@localhost ~]# echo $c
30
[root@localhost ~]#
定义变量保存命令结果
[root@localhost ~]# result=$(ls )
[root@localhost ~]# echo $result
anaconda-ks.cfg jiaowu.sql mysqlbak
[root@localhost ~]#
交互式变量赋值
[root@localhost ~]# read -p "请输入密码" passwd
请输入密码123456
[root@localhost ~]# echo $passwd
123456
环境变量
1.查看环境变量
[root@node01 ~]# env
2.定义环境变量
# export 变量名称=值 3.定义在历史命令中显示时间
[root@localhost ~]# history
1 cd /etc/yum.repos.d/
2 ls
3 mv CentOS-Base.repo CentOS-Base.repo.bak
4 mv CentOS-Base.repo.bak CentOS-Base.repo
5 yum install wget
[root@localhost ~]# vim /etc/profile
76 unset -f pathmunge
77 export HISTTIMEFORMAT="%F_%T"
[root@localhost ~]# source /etc/profile
[root@localhost ~]# history
1 2020-09-22_04:37:47cd /etc/yum.repos.d/
2 2020-09-22_04:37:47ls
3 2020-09-22_04:37:47mv CentOS-Base.repo CentOS-Base.repo.bak
4 2020-09-22_04:37:47mv CentOS-Base.repo.bak CentOS-Base.repo
5 2020-09-22_04:37:47yum install wget
6 2020-09-22_04:37:47yum install vim
7 2020-09-22_04:37:47cd
8 2020-09-22_04:37:47systemctl disable firewalld
9 2020-09-22_04:37:47cd /etc/selinux/
10 2020-09-22_04:37:47ls
简单的脚本设计
1.设计一个创建用户的脚本
[root@localhost shell]# vim useradd.sh
in/bash
2
3
4 useradd liuyan
5 echo "ly"|passwd --stdin liuyan &> /etc/null
6
7
[root@localhost shell]# bash ./useradd.sh
[root@localhost shell]# id liuyan
uid=1000(liuyan) gid=1000(liuyan) groups=1000(liuyan)
2.设计一个交互式创建用户脚本
[root@localhost shell]# vim ./useradd.sh
in/bash
2
3 read -p "用户名：" name
4 read -p "密码：" password
5
6
7
8
9 useradd $name
10
11 echo "$password"|passwd --stdin $name &> /etc/null
12
13
14 echo "用户创建完成"
15
16
[root@localhost shell]# userdel liuyan
[root@localhost shell]#
[root@localhost shell]#
[root@localhost shell]#
[root@localhost shell]# id liuyan
id: liuyan: no such user
[root@localhost shell]#
[root@localhost shell]#
[root@localhost shell]#
[root@localhost shell]# bash ./useradd.sh
用户名：liuyan
密码：ly
useradd: warning: the home directory already exists.
Not copying any file from skel directory into it.
Creating mailbox file: File exists
用户创建完成
[root@localhost shell]#
逻辑控制语句——if语句
语法
if 条件; then
执行的操作
执行的操作
fi
数字表达式
| 表达式 | 作用 |
|---|---|
| [ number1 -eq number2 ] | 等于 |
| [ number1 -ne number2 ] | 不等于 |
| [ number1 -gt number2 ] | 大于 |
| [ number1 -ge number2 ] | 大于等于 |
| [ number1 -lt number2 ] | 小于 |
| [ number1 -le number2 ] | 小于等 |
1.设计一个简单的创建用户脚本
[root@localhost shell]# vim checkuser.sh
Error detected while processing /root/.vimrc:
line 1:
E518: Unknown option: #行号
line 2:
E518: Unknown option: #行标准线
line 3:
E518: Unknown option: #自动缩进
line 4:
E518: Unknown option: #tab标准
Press ENTER or type command to continue
1 #!/bin/bash
2
3 read -p "用户名：" name
4 id $name &> /dev/null
5
6
7 if [ $? -ne 0 ]; then
8 useradd $name
9 echo "$name" |passwd -stdin $name &> /dev/null
10 echo "用户$name 已经创建,初始密码是用户名"
11
12
13 else
14 echo "创建失败"
15 fi
逻辑控制语句——case语句
语法
case 变量 in
值1)
执行操作
执行操作
;;
值2)
执行操作
执行操作
;;
示例一
[root@localhost shell]# vim case.sh
1 #!/bin/bash
2
3 read -p "请输入：" data
4 case $data in
5 linux|Linux)
6 echo "Centos"
7 ;;
8 windows)
9 echo "Windows10"
10 ;;
11 *)
12 echo "NO"
13 ;;
14 esac
位置变量
$1, $2, $3…$9, ${10} $1：第一个参数
$0
命令本身
$#
参数个数
示例一
[root@localhost shell]# vim case.sh
1 #!/bin/bash
2
3 case $1 in
4 linux)
5 echo "Centos"
6 ;;
7 windows)
8 echo "Windows10"
9 ;;
10 *)
11 echo "NO"
12 ;;
13 esac
[root@localhost shell]# chmod a+x ./case.sh
[root@localhost shell]#
[root@localhost shell]#
[root@localhost shell]# ./case.sh lll
NO
示例二
[root@localhost shell]# vim case.sh
1 #!/bin/bash
2
3 if [ $# == 0 ]; then
4 echo "error"
5 exit 10
6 fi
7
8
9 case $1 in
10 linux)
11 echo "Centos"
12 ;;
13 windows)
14 echo "Windows10"
15 ;;
16 *)
17 echo "NO"
18 ;;
19 esac
20
[root@localhost shell]# ./case.sh dsf
NO
[root@localhost shell]# ./case.sh linux
Centos
[root@localhost shell]# ./case.sh
error利用脚本进行nginx测试
1.安装nginx
[root@bogon data]# wget http://nginx.org/download/nginx-1.18.0.tar.gz
--2020-10-01 22:45:37-- http://nginx.org/download/nginx-1.18.0.tar.gz
Resolving nginx.org (nginx.org)... 52.58.199.22, 3.125.197.172, 2a05:d014:edb:5704::6, ...
Connecting to nginx.org (nginx.org)|52.58.199.22|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1039530 (1015K) [application/octet-stream]
Saving to: ‘nginx-1.18.0.tar.gz’
[root@bogon data]# yum -y install gcc zlib zlib-devel pcre-devel openssl openssl-devel
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.huaweicloud.com
* extras: mirrors.huaweicloud.com
* updates: mirrors.ustc.edu.cn
[root@bogon data]# tar -xvf nginx-1.18.0.tar.gz
nginx-1.18.0/
nginx-1.18.0/auto/
nginx-1.18.0/conf/
nginx-1.18.0/contrib/
nginx-1.18.0/src/
nginx-1.18.0/configure
[root@bogon ~]# cd /usr/local/
[root@bogon local]# ls
bin etc games include lib lib64 libexec sbin share src
[root@bogon local]# cp -r /root/data/nginx ./
[root@bogon local]# ls
bin etc games include lib lib64 libexec nginx sbin share src
[root@bogon nginx-1.18.0]# ./configure
checking for OS
+ Linux 3.10.0-327.el7.x86_64 x86_64
checking for C compiler ... found
+ using GNU C compiler
+ gcc version: 4.8.5 20150623 (Red H
[root@bogon nginx-1.18.0]# make
make -f objs/Makefile
make[1]: Entering directory `/usr/local/nginx/nginx-1.18.0'
cc -c -pipe -O -W -Wall -Wpointer-arith -Wno-unused-parameter -Werror -g -I src/core -I src/event -I src/event/modules -I src/os/unix -I
[root@bogon nginx-1.18.0]# make install
make -f objs/Makefile install
make[1]: Entering director
[root@bogon nginx]# ls
conf html logs nginx-1.18.0 sbin
[root@bogon nginx]# cd sbin/
[root@bogon sbin]# ls
nginx
2.利用脚本控制nginx
[root@bogon shell]# vim nginxctl
1#!bin/bash
2
3
4 nginx=/usr/local/nginx/sbin/nginx
5
6 #检测参数是否存在
7 if [ $# == 0 ]; then
8 echo "请输入参数"
9 exit 10
10 fi
11
12 case $1 in
13 start)
14 $nginx
15 if [ $? == 0 ]; then
16 echo "nginx启动成功"
17 fi
18 ;;
19 stop)
20 $nginx -s stop
21 if [ $? == 0 ]; then
22 echo "nginx关闭成功"
23 fi
24 ;;
25 restart)
26 $nginx -s stop
27 if [ $? == 0 ]; then
28 sleep 1
29 $nginx
30 else
31 echo "执行失败"
32 fi
33 ;;
34 esac
35
36
37
[root@bogon shell]# bash ./nginxctl.sh
请输入参数
[root@bogon shell]# bash ./nginxctl.sh start
nginx启动成功
[root@bogon shell]# bash ./nginxctl.sh stop
nginx关闭成功
逻辑控制语句——for语句
语法:
for 变量 in 取值列表; do
执行的操作
执行的操作
done
[root@bogon shell]# vim for.sh
1#!bin/bash
2
3 for i in {1..10}; do
4 echo "$i"
5 done
[root@bogon shell]# bash ./for.sh
1
2
3
4
5
6
7
8
9
10
1 #!/bin/bash
2
3 for i in $(seq 10); do
4 echo "$i"
5 done
[root@bogon shell]# bash ./for.sh
1
2
3
4
5
6
7
8
9
10
1 #!/bin/bash
2
3 for i in $(seq 2 10); do
4 echo "$i"
5 done
[root@bogon shell]# bash ./for.sh
2
3
4
5
6
7
8
9
10
1 #!/bin/bash
2
3 for i in $(seq 1 2 10); do
4 echo "$i"
5 done
[root@bogon shell]# bash ./for.sh
1
3
5
7
9
#!/bin/bash
#
for i in $(seq 20); do
if id user$i &> /dev/null; then
echo "用户user$i存在"
else
useradd user$i
echo "redhat" | passwd ‐‐stdin user$i &> /dev/null
echo "用户user$i创建完成, 初始密码为redhat"
fi
done
中断语句
continue 中断本次循环, 立刻开始执行下一次循环
break 中断整体循环
1#!/bin/bash
2 #
3
4 for i in $(seq 5); do
5 echo "第$i次循环开始"
6 if [ $i ‐eq 2 ]; then
7 continue
8 fi
9 echo "‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐"
10 echo "第$i次循环结束"
11 done 1 #!/bin/bash
2 #
3
4 for i in $(seq 5); do
5 echo "第$i次循环开始"
6 if [ $i ‐eq 2 ]; then
7 break
8 fi
9 echo "‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐"
10 echo "第$i次循环结束"
11 done
[root@localhost shell]# vim ping.sh
1 #!/bin/bash
2
3
4 net=192.168.122.
5 for i in $(seq 254); do
6 if ping -c 1 -W 1 $net$i &> /dev/null; then
7 echo "$net$i 正常"
8 fi
9 done
[root@localhost shell]# bash ./ping.sh
192.168.122.1 正常
192.168.122.2 正常
192.168.122.10 正常
截取IP和MAC地址
2 #!/bin/bash
3 #
4
5 local_ip=$(ifconfig ens33 | grep "netmask" | awk '{print $2}') 6 local_mac=$(ifconfig ens33 | grep "ether" | awk '{print $2}')
7
8 echo "本地IP地址: $local_ip 本地MAC地址: $local_mac"
9
10
11 for i in $(seq 254); do
12 if [ $i ‐eq 10 ]; then
13 continue
14 fi
15
16 if ping 192.168.183.$i &> /dev/null; then
17 mac_addr=$(arping ‐I ens33 ‐c 1 ‐w 1 192.168.183.$i | grep "Unicast" | awk '{print $5}')
18 echo "IP地址: 192.168.183.$i MAC地址: $mac_addr"
19 fi
20 doneshell中的字符串处理
[root@node01 ~]# str01=linux
[root@node01 ~]# echo ${#str01} #字符串长度
5
[root@node01 ~]# echo ${str01:1:2} #从字符串第号开始到第二号结束
in
[root@node01 ~]# echo ${str01:1:3} #从字符串第号开始到第三号结束
inu
[root@node01 ~]# echo ${str01:2} #从字符串第二号开始到结尾
nux
替换
[root@node01 ~]# filename=/opt/bj/a.txt
[root@node01 ~]#
[root@node01 ~]# echo ${filename/bj/sh}
/opt/sh/a.txt [root@node01 ~]# str01="linux linux mac linux"
[root@node01 ~]# echo ${str01//linux/IBM}
IBM IBM mac IBM 大小写替换
[root@node01 ~]# str01="AbCd"
[root@node01 ~]# echo ${str01,}
abCd
[root@node01 ~]# echo ${str01,,}
abcd
[root@node01 ~]# str01="aBcD"
[root@node01 ~]# echo ${str01^}
ABcD
[root@node01 ~]# echo ${str01^^}
ABCD文件校验脚本
[root@localhost shell]# vim testfile.sh
in/bash
2
3 for sname in $(find /root/shell - name "*.*"); do
4 dname=${sname/shell/shellbak}
5 if [ ! -e $dname ]; then
6 echo "文件$dname丢失"
7 else
8 smd5=$(md5sum $sname |awk '{print $1}')
9 dmd5=$(md5sum $dname |awk '{print $1}')
10 if [ $smd5 != $dmd5 ]; then
11 echo "文件$dname数据错误"
12 fi
13 fi
14 done
~ 逻辑控制语句——while语句
语法
while 条件; do
执行的操作
执行的操作
改变条件真假的语句
done
1 #!/bin/bash
2 #
3
4 network=192.168.183.
5
6 i=1
7
8 while [ $i ‐le 254 ]; do
9 if ping ‐c 1 ‐W 1 $network$i &> /dev/null; then
10 echo "Host $network$i is up"
11 fi
12 let i++
13 done
1 #!/bin/bash
2 #
3
4 while read line; do
5 name=$(echo $line | awk ‐F: '{print $1}')
6 user_id=$(echo $line | awk ‐F: '{print $3}')
7 group_id=$(echo $line | awk ‐F: '{print $4}')
8 comment=$(echo $line | awk ‐F: '{print $5}')
9 home_dir=$(echo $line | awk ‐F: '{print $6}')
10 sh_name=$(echo $line | awk ‐F: '{print $7}')
11
12 mysql ‐uroot ‐e "insert into testdb.userInfo(name,user_id,group_id,comm ent,home_dir,sh_name) values('$name',$user_id,$group_id,'$comment','$home_d ir','$sh_name')"
13 done < /etc/passwd应用案例
1 #!/bin/bash
2 #
3
4 l_number=0 5 e_number=0
6
7 while read line; do
8 status=$(echo $line | awk '{print $6}')
9 if [ $status == "LISTEN" ]; then
10 let l_number++
11 elif [ $status == "ESTABLISHED" ]; then 12 let e_number++ 13 fi
14 done < <(netstat ‐antp | grep "^tcp")
15
16 echo "Listen状态数量: $l_number函数的相关学习
优势:
1. 方便功能的重复使用
2. 方便二次修改
语法1:
1 函数名称()
{ 2 … 3 … 4 … 5 }
语法2:
1 function 函数名称()
{ 2 … 3 … 4 … 5 }
1 #!/bin/bash
2 #
3
4 # 添加用户
5 createUser() {
6 read ‐p "用户名：" username
7 if id $username &> /dev/null; then
8 echo "用户$username存在"
9 else
10 useradd $username
11 echo "用户$username创建完成"
12 fi
13 }
14
15
16 # 删除用户 $1 用户名
17 removeUser() {
18 if id $1 &> /dev/null; then
19 userdel ‐r $1
20 echo "用户$1删除成功"
21 else
22 echo "用户$1不存在"
23 fi
24 }
25
26 # 修改用户shell, $1用户名 $2 shell名称
27 modifyUser() {
28 if id $1 &> /dev/null; then
29 old_sh_name=$(grep "^$1:" /etc/passwd | awk ‐F: '{print $7}')
30 echo "用户$1当前使用的shell为: $old_sh_name"
31 usermod ‐s $2 $1
32 echo "用户$1的shell被修改为$2"
33 fi
34
35 }
36
37 cat << eof
38 ‐‐‐‐用户管理‐‐‐‐
39 1. 添加用户
40 2. 删除用户
41 3. 修改用户信息
42 4. 退出
43 eof
44
45 while true; do
46 read ‐p "选择: " choice
47 case $choice in
48 1)
49 createUser
50 ;;
51 2)
52 read ‐p "用户名: " username
53 removeUser $username
54 ;;
55 3)
56 read ‐p "用户名: " username
57 read ‐p "shell名称: " sh_name
58 modifyUser $username $sh_name
59 ;;
60 4)
61 echo "Bye‐‐bye "
62 exit 8expect工具的使用
作用：捕获交互式的输出，根据输出自动发送参数
1.捕获远程拷贝文件的命令相关信息（scp）
1 #!/usr/bin/expect
2 #
3
4 set timeout 3
5
6 spawn scp /etc/fstab root@192.168.183.11:/tmp
7 expect " password:"
8 send "redhat\n"
9
10 expect eof
[root@localhost ~]# expect ./text
2.结合shell脚本使用expect
1 #!/bin/bash
2 #
3
4 read ‐p "文件名称: " file_name
5
6 if [ ‐e $file_name ]; then
7 /usr/bin/expect << eof
8 set timeout 3
9 spawn scp $file_name root@192.168.183.11:/tmp
10 expect "password:"
11 send "redhat\n"
12 expect eof
13 eof
14 fi
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