一、简介

　　在shell脚本编写中，时常会用到对文件的相关操作，比如增加内容，修改内容，删除部分内容，查看部分内容等，但是上述举例的这些操作一般都是需要在文本编辑器中才能操作，常用的文本编辑器如：gedit、vim、nano等又是交互式文本编辑器，脚本无法自己独立完成，必须有人参与才可以完成。如果这样的话又违背了我们编写脚本的意愿(全部由机器来完成，减少人的工作压力，提升工作效率)。emm…如何才能让这些操作全部脚本自己就搞定，而不需要人的参与，而且又能按照我们的脚本预案来完成呢？

为了解决上述问题，linux为大家提供了一些命令，比如Perl、sed等命令，着重介绍一下sed命令。

二、sed命令

1、sed介绍

         sed是linux中提供的一个外部命令,它是一个行(流)编辑器，非交互式的对文件内容进行增删改查的操作，使用者只能在命令行输入编辑命令、指定文件名，然后在屏幕上查看输出。它和文本编辑器有本质的区别。

也就是前者一次处理一个文本，而后者是一次处理一个文本中的一行。这个是我们应该弄清楚且必须牢记的，否者可能无法理解sed的运行原理和使用精髓。

sed数据处理原理：

2、sed语法

sed 命令语法：

sed [options] ‘{command}[flags]’ [filename]

命令选项：

-e script 将脚本中指定的命令添加到处理输入时执行的命令中  多条件，一行中要有多个操作
-f script 将文件中指定的命令添加到处理输入时执行的命令中
-n        抑制自动输出
-i        编辑文件内容
-i.bak    修改时同时创建.bak备份文件。
-r        使用扩展的正则表达式
!         取反 （跟在模式条件后与shell有所区别）

command   对文件干什么

sed常用内部命令
a   在匹配后面添加
i   在匹配前面添加
d   删除
s   查找替换  字符串
c   更改
y   转换   N D P 
p   打印



#flags
数字             表示新文本替换的模式
g：             表示用新文本替换现有文本的全部实例
p：             表示打印原始的内容
w filename:     将替换的结果写入文件

3，演示示例

先准备一个文件

（1）command演示

[root@CentOs shell]# vim data

1 the quick brown fox jumps over the lazy dog.

2 the quick brown fox jumps over the lazy dog.

3 the quick brown fox jumps over the lazy dog.

4 the quick brown fox jumps over the lazy dog.

5 the quick brown fox jumps over the lazy dog.

a添加后面命令：

[root@CentOs shell]# sed 'a\hello,world' data
1 the quick brown fox jumps over the lazy dog.
hello,world
2 the quick brown fox jumps over the lazy dog.
hello,world
3 the quick brown fox jumps over the lazy dog.
hello,world
4 the quick brown fox jumps over the lazy dog.
hello,world
5 the quick brown fox jumps over the lazy dog.
hello,world
[root@CentOs shell]#

[root@CentOs shell]# sed '3a\hello,world' data （对第三行追加）
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
3 the quick brown fox jumps over the lazy dog.
hello,world
4 the quick brown fox jumps over the lazy dog.
5 the quick brown fox jumps over the lazy dog.
[root@CentOs shell]#

[root@CentOs shell]# sed '2,4a\hello,world' data
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
hello,world
3 the quick brown fox jumps over the lazy dog.
hello,world
4 the quick brown fox jumps over the lazy dog.
hello,world
5 the quick brown fox jumps over the lazy dog.
[root@CentOs shell]#

[root@CentOs shell]# sed '/3 the/a\hello,world' data （“//”是开启匹配模式，这个生产环境中常用！！！）
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
3 the quick brown fox jumps over the lazy dog.
hello,world
4 the quick brown fox jumps over the lazy dog.
5 the quick brown fox jumps over the lazy dog.
[root@CentOs shell]#

i插入前面命令：

[root@CentOs shell]# sed '/3 the/i\hello,world' data
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
hello,world
3 the quick brown fox jumps over the lazy dog.
4 the quick brown fox jumps over the lazy dog.
5 the quick brown fox jumps over the lazy dog.
[root@CentOs shell]#

d删除命令：

[root@CentOs shell]# sed '/3 the/d' data
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
4 the quick brown fox jumps over the lazy dog.
5 the quick brown fox jumps over the lazy dog.

[root@CentOs shell]# cp /usr/local/nginx/conf/nginx.conf .

[root@CentOs shell]# sed -r '/^#/d' nginx.conf  （删除以#开头的行）

[root@CentOs shell]# sed -r '/(^#|#|^$)/d' nginx.conf  （删除以#开头或者包含#或者空行的行）
worker_processes  1;
events {
    worker_connections  1024;
}
http {
    include       mime.types;
    default_type  application/octet-stream;
    sendfile        on;
    keepalive_timeout  65;
    server {
        listen       80;
        server_name  localhost;
        location / {
            root   html;
            index  index.html index.htm;
        }
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }
    }
}
[root@CentOs shell]#

s替换命令：

[root@CentOs shell]# cat data
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
3 the quick brown fox jumps over the lazy dog.
4 the quick brown fox jumps over the lazy dog.
5 the quick brown fox jumps over the lazy dog.
[root@CentOs shell]# sed 's/dog/cat/' data （把dog替换成cat）
1 the quick brown fox jumps over the lazy cat.
2 the quick brown fox jumps over the lazy cat.
3 the quick brown fox jumps over the lazy cat.
4 the quick brown fox jumps over the lazy cat.
5 the quick brown fox jumps over the lazy cat.
[root@CentOs shell]#

[root@CentOs shell]# sed '/3 the/s/dog/cat/' data
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
3 the quick brown fox jumps over the lazy cat.
4 the quick brown fox jumps over the lazy dog.
5 the quick brown fox jumps over the lazy dog.
[root@CentOs shell]#

c更改命令

[root@CentOs shell]# sed '/3 the/c\hello world' data
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
hello world
4 the quick brown fox jumps over the lazy dog.
5 the quick brown fox jumps over the lazy dog.
[root@CentOs shell]#

[root@CentOs shell]# sed '2,4c\hello world' data（这个有点特殊，把2-4行删除，再添加）
1 the quick brown fox jumps over the lazy dog.
hello world
5 the quick brown fox jumps over the lazy dog.
[root@CentOs shell]#

y转换命令：

[root@CentOs shell]# sed 'y/abcdefg/ABCDEFG/' data
1 thE quiCk Brown Fox jumps ovEr thE lAzy DoG.
2 thE quiCk Brown Fox jumps ovEr thE lAzy DoG.
3 thE quiCk Brown Fox jumps ovEr thE lAzy DoG.
4 thE quiCk Brown Fox jumps ovEr thE lAzy DoG.
5 thE quiCk Brown Fox jumps ovEr thE lAzy DoG.
[root@CentOs shell]#

p打印命令

[root@CentOs shell]# sed 'p' data （出现两行，是因为把内存和文件都打印了出来！！！）
1 the quick brown fox jumps over the lazy dog.
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
3 the quick brown fox jumps over the lazy dog.
3 the quick brown fox jumps over the lazy dog.
4 the quick brown fox jumps over the lazy dog.
4 the quick brown fox jumps over the lazy dog.
5 the quick brown fox jumps over the lazy dog.
5 the quick brown fox jumps over the lazy dog.
[root@CentOs shell]#

[root@CentOs shell]# sed '/3 the/p' data
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
3 the quick brown fox jumps over the lazy dog.
3 the quick brown fox jumps over the lazy dog.
4 the quick brown fox jumps over the lazy dog.
5 the quick brown fox jumps over the lazy dog.
[root@CentOs shell]#

（2）flags演示

数字：

[root@CentOs shell]# cat data
1 the quick brown fox jumps over the lazy dog.dog
2 the quick brown fox jumps over the lazy dog.dog
3 the quick brown fox jumps over the lazy dog.dog
4 the quick brown fox jumps over the lazy dog.dog
5 the quick brown fox jumps over the lazy dog.dog
[root@CentOs shell]# sed 's/dog/cat/' data
1 the quick brown fox jumps over the lazy cat.dog
2 the quick brown fox jumps over the lazy cat.dog
3 the quick brown fox jumps over the lazy cat.dog
4 the quick brown fox jumps over the lazy cat.dog
5 the quick brown fox jumps over the lazy cat.dog
[root@CentOs shell]# sed 's/dog/cat/2' data
1 the quick brown fox jumps over the lazy dog.cat
2 the quick brown fox jumps over the lazy dog.cat
3 the quick brown fox jumps over the lazy dog.cat
4 the quick brown fox jumps over the lazy dog.cat
5 the quick brown fox jumps over the lazy dog.cat
[root@CentOs shell]#

g：全部替换

[root@CentOs shell]# sed 's/dog/cat/g' data
1 the quick brown fox jumps over the lazy cat.cat
2 the quick brown fox jumps over the lazy cat.cat
3 the quick brown fox jumps over the lazy cat.cat
4 the quick brown fox jumps over the lazy cat.cat
5 the quick brown fox jumps over the lazy cat.cat
[root@CentOs shell]#

p：打印输出

[root@CentOs shell]# sed '3s/dog/cat/p' data
1 the quick brown fox jumps over the lazy dog.dog
2 the quick brown fox jumps over the lazy dog.dog
3 the quick brown fox jumps over the lazy cat.dog
3 the quick brown fox jumps over the lazy cat.dog
4 the quick brown fox jumps over the lazy dog.dog
5 the quick brown fox jumps over the lazy dog.dog
[root@CentOs shell]#

w filename：将替换的结果写入文件中

[root@CentOs shell]# sed '3s/dog/cat/w newfile data
1 the quick brown fox jumps over the lazy dog.dog
2 the quick brown fox jumps over the lazy dog.dog
3 the quick brown fox jumps over the lazy cat.dog
4 the quick brown fox jumps over the lazy dog.dog
5 the quick brown fox jumps over the lazy dog.dog
[root@CentOs shell]# ls
data        ip.txt   nginx.conf           ShellTest.sh  zzku.sh
fenjie.txt  newfile  NginxTestfailing.sh  test01.sh
[root@CentOs shell]# cat newfile
3 the quick brown fox jumps over the lazy cat.dog
[root@CentOs shell]#

（3）命令选项

-n：只输入自己想要的那部分

[root@CentOs shell]# sed -n '3s/dog/cat/p' data
3 the quick brown fox jumps over the lazy cat.dog
[root@CentOs shell]#

-e：多条件，一行中要有多个操作

[root@CentOs shell]# sed -e 's/brown/grey/;s/dog/cat/' data
1 the quick grey fox jumps over the lazy cat.dog
2 the quick grey fox jumps over the lazy cat.dog
3 the quick grey fox jumps over the lazy cat.dog
4 the quick grey fox jumps over the lazy cat.dog
5 the quick grey fox jumps over the lazy cat.dog
[root@CentOs shell]#

-f：将文件中的命令添加到处理输入时执行的命令中

[root@CentOs shell]# vim file
[root@CentOs shell]# cat file
s/brown/grey/
s/dog/cat/
[root@CentOs shell]# sed -f file data
1 the quick grey fox jumps over the lazy cat.dog
2 the quick grey fox jumps over the lazy cat.dog
3 the quick grey fox jumps over the lazy cat.dog
4 the quick grey fox jumps over the lazy cat.dog
5 the quick grey fox jumps over the lazy cat.dog
[root@CentOs shell]#

-i：修改源文件（不可逆）

[root@CentOs shell]# sed -i 's/dog/cat/g' data
[root@CentOs shell]# cat data
1 the quick brown fox jumps over the lazy cat.cat
2 the quick brown fox jumps over the lazy cat.cat
3 the quick brown fox jumps over the lazy cat.cat
4 the quick brown fox jumps over the lazy cat.cat
5 the quick brown fox jumps over the lazy cat.cat
[root@CentOs shell]#

[root@CentOs shell]# sed -i.bak 's/cat/dog/g' data（使用-i时，可以备份一个文件）

[root@CentOs shell]# ls
data      fenjie.txt  ip.txt      NginxTestfailing.sh  test01.sh
data.bak  file        nginx.conf  ShellTest.sh         zzku.sh
[root@CentOs shell]# cat data.bak （源文件的备份还是没有变化）
1 the quick brown fox jumps over the lazy cat.cat
2 the quick brown fox jumps over the lazy cat.cat
3 the quick brown fox jumps over the lazy cat.cat
4 the quick brown fox jumps over the lazy cat.cat
5 the quick brown fox jumps over the lazy cat.cat
[root@CentOs shell]# cat data（源文件已被修改）
1 the quick brown fox jumps over the lazy dog.dog
2 the quick brown fox jumps over the lazy dog.dog
3 the quick brown fox jumps over the lazy dog.dog
4 the quick brown fox jumps over the lazy dog.dog
5 the quick brown fox jumps over the lazy dog.dog
[root@CentOs shell]#

-r：使用正则表达式

[root@CentOs shell]# sed -r -n '/^(root)(.*)(bash)$/p' /etc/passwd（打印以root开头、中间任意、结尾以bash结束的行）
root:x:0:0:root:/root:/bin/bash
[root@CentOs shell]#

！：取反

我们也不一定非得使用文件输出。以管道为例：

[root@CentOs shell]# echo "Tom is cool"|sed 's/Tom is/I am/'
I am cool
[root@CentOs shell]#

三、sed的一些小技巧

$=：统计行号

[root@CentOs shell]# sed -n '$=' data
5
[root@CentOs shell]#

=：给每一行加行号

[root@CentOs shell]# sed '=' data
1
1 the quick brown fox jumps over the lazy dog.dog
2
2 the quick brown fox jumps over the lazy dog.dog
3
3 the quick brown fox jumps over the lazy dog.dog
4
4 the quick brown fox jumps over the lazy dog.dog
5
5 the quick brown fox jumps over the lazy dog.dog
[root@CentOs shell]#

四、写一个搭建ftp服务的脚本

要求如下：

1）不支持本地用户登录 local_enable=NO
2） 匿名用户可以上传 新建 删除 anon_upload_enable=YES anon_mkdir_write_enable=YES
3） 匿名用户限速500KBps anon_max_rate=500000

仅供参考：
#!/bin/bash
ipaddr=`ifconfig eth0|sed -n '2p'|sed -e 's/.*inet addr:\(.*\) Bcast.*/\1/g'`
iptail=`echo $ipaddr|cut -d'.' -f4`
ipremote=192.168.1.10
#修改主机名
hostname server$iptail.zutuanxue.com
sed -i "/HOSTNAME/cHOSTNAME=server$iptail.zutuanxue.com" /etc/sysconfig/network
echo "$ipaddr server$iptail.zutuanxue.cc" >>/etc/hosts
#关闭防火墙和selinux
service iptables stop
setenforce 0 >/dev/null 2>&1
sed -i '/^SELINUX=/cSELINUX=disabled' /etc/selinux/config
#配置yum源(一般是内网源)
#test network
ping -c 1 $ipremote > /dev/null 2>&1
if [ $? -ne 0 ];then
	echo "你的网络不通，请先检查你的网络"
	exit 1
else
	echo "网络ok."
fi
cat > /etc/yum.repos.d/server.repo << end
[server]
name=server
baseurl=ftp://$ipremote
enabled=1
gpgcheck=0
end

#安装软件
read -p "请输入需要安装的软件，多个用空格隔开：" soft
yum -y install $soft &>/dev/null

#备份配置文件
conf=/etc/vsftpd/vsftpd.conf
\cp $conf $conf.default
#根据需求修改配置文件
sed -ir '/^#|^$/d' $conf
sed -i '/local_enable/c\local_enable=NO' $conf
sed -i '$a anon_upload_enable=YES' $conf
sed -i '$a anon_mkdir_write_enable=YES' $conf
sed -i '$a anon_other_write_enable=YES' $conf
sed -i '$a anon_max_rate=512000' $conf
#启动服务
service vsftpd restart &>/dev/null && echo"vsftpd服务启动成功"

#测试验证
chmod 777 /var/ftp/pub
cp /etc/hosts /var/ftp/pub
#测试下载
cd /tmp
lftp $ipaddr <<end
cd pub
get hosts
exit
end

if [ -f /tmp/hosts ];then
	echo "匿名用户下载成功"
	rm -f /tmp/hosts
else
	echo "匿名用户下载失败"
fi
#测试上传、创建目录、删除目录等
cd /tmp
lftp $ipaddr << end
cd pub
mkdir test1
mkdir test2
put /etc/group
rmdir test2
exit
end

if [ -d /var/ftp/pub/test1 ];then
    echo "创建目录成功"
	if [ ! -d /var/ftp/pub/test2 ];then
    	echo "文件删除成功"
        fi
else
	if [ -f /var/ftp/pub/group ];then
	echo "文件上传成功"
        else
        echo "上传、创建目录删除目录部ok"
        fi 
fi   
[ -f /var/ftp/pub/group ] && echo "上传文件成功"