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,今天我就着重为大家介绍一下sed命令。
一、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。区别是: 文本编辑器: 编辑对象是文件 行编辑器:编辑对象是文件中的行
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
二、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
2.1)sed内部命令说明
演示实例文档
[root@zutuanxue ~]# cat data1
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.
文件内容增加操作,将数据追加到某个位置之后,使用命令a。
演示案例
在data1的每行后追加一行新数据内容: append data "haha"
[root@zutuanxue ~]# sed 'a\append data "haha"' data1
1 the quick brown fox jumps over the lazy dog.
append data "haha"
2 the quick brown fox jumps over the lazy dog.
append data "haha"
3 the quick brown fox jumps over the lazy dog.
append data "haha"
4 the quick brown fox jumps over the lazy dog.
append data "haha"
5 the quick brown fox jumps over the lazy dog.
append data "haha"
在第二行后新开一行追加数据: append data "haha"
[root@zutuanxue ~]# sed '2a\append data "haha"' data1
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
append data "haha"
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.
在第二到四行每行后新开一行追加数据: append data "haha"
[root@zutuanxue ~]# sed '2,4a\append data "haha"' data1
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
append data "haha"
3 the quick brown fox jumps over the lazy dog.
append data "haha"
4 the quick brown fox jumps over the lazy dog.
append data "haha"
5 the quick brown fox jumps over the lazy dog.
匹配字符串追加: 找到包含"3 the"的行,在其后新开一行追加内容: append data "haha"
[root@zutuanxue ~]# sed '/3 the/a\append data "haha"' data1
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.
append data "haha"
4 the quick brown fox jumps over the lazy dog.
5 the quick brown fox jumps over the lazy dog.
//开启匹配模式 /要匹配的字符串/
文件内容增加操作,将数据插入到某个位置之前,使用命令i。
演示案例
在data1的每行前插入一行新数据内容: insert data "haha"
[root@zutuanxue ~]# sed 'i\insert data "haha"' data1
insert data "haha"
1 the quick brown fox jumps over the lazy dog.
insert data "haha"
2 the quick brown fox jumps over the lazy dog.
insert data "haha"
3 the quick brown fox jumps over the lazy dog.
insert data "haha"
4 the quick brown fox jumps over the lazy dog.
insert data "haha"
5 the quick brown fox jumps over the lazy dog.
在第二行前新开一行插入数据: insert data "haha"
[root@zutuanxue ~]# sed '2i\insert data "haha"' data1
1 the quick brown fox jumps over the lazy dog.
insert data "haha"
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.
在第二到四行每行前新开一行插入数据: insert data "haha"
[root@zutuanxue ~]# sed '2,4i\insert data "haha"' data1
1 the quick brown fox jumps over the lazy dog.
insert data "haha"
2 the quick brown fox jumps over the lazy dog.
insert data "haha"
3 the quick brown fox jumps over the lazy dog.
insert data "haha"
4 the quick brown fox jumps over the lazy dog.
5 the quick brown fox jumps over the lazy dog.
匹配字符串插入: 找到包含"3 the"的行,在其前新开一行插入内容: insert data "haha"
[root@zutuanxue ~]# sed '/3 the/i\insert data "haha"' data1
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
insert data "haha"
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.
文件内容修改操作–替换,将一行中匹配的内容替换为新的数据,使用命令s。
演示案例
从标准输出流中做替换,将test替换为text
[root@zutuanxue ~]# echo "this is a test" |sed 's/test/text/'
this is a text
将data1中每行的dog替换为cat
[root@zutuanxue ~]# sed 's/dog/cat/' data1
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.
将data1中第二行的dog替换为cat
[root@zutuanxue ~]# sed '2s/dog/cat/' data1
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy cat.
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.
将data1中第二到第四行的dog替换为cat
[root@zutuanxue ~]# sed '2,4s/dog/cat/' data1
1 the quick brown fox jumps over the lazy dog.
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 dog.
匹配字符串替换:将包含字符串"3 the"的行中的dog替换为cat
[root@zutuanxue ~]# sed '/3 the/s/dog/cat/' data1
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.
文件内容修改操作–更改,将一行中匹配的内容替换为新的数据,使用命令c。
演示案例
将data1文件中的所有行的内容更改为: change data "data"
[root@zutuanxue ~]# sed 'c\change data "haha"' data1
change data "haha"
change data "haha"
change data "haha"
change data "haha"
change data "haha"
将data1文件第二行的内容更改为: change data "haha"
[root@zutuanxue ~]# sed '2c\change data "haha"' data1
1 the quick brown fox jumps over the lazy dog.
change data "haha"
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.
将data1文件中的第二、三、四行的内容更改为:change data "haha"
[root@zutuanxue ~]# sed '2,4c\change data "haha"' data1
1 the quick brown fox jumps over the lazy dog.
change data "haha"
5 the quick brown fox jumps over the lazy dog.
将data1文件中包含"3 the"的行内容更改为: change data "haha"
[root@zutuanxue ~]# sed '/3 the/c\change data "data"' data1
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
change data "data"
4 the quick brown fox jumps over the lazy dog.
5 the quick brown fox jumps over the lazy dog.
文件内容修改操作–字符转换,将一行中匹配的内容替换为新的数据,使用命令y。
演示案例
将data1中的a b c字符转换为对应的 A B C字符
[root@zutuanxue ~]# sed 'y/abc/ABC/' data1
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.
文件内容删除,将文件中的指定数据删除,使用命令d。
演示案例
删除文件data1中的所有数据
[root@zutuanxue ~]# sed 'd' data1
删除文件data1中的第三行数据
[root@zutuanxue ~]# sed '3d' data1
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.
删除文件data1第三到第四行的数据
[root@zutuanxue ~]# sed '3,4d' data1
1 the quick brown fox jumps over the lazy dog.
2 the quick brown fox jumps over the lazy dog.
5 the quick brown fox jumps over the lazy dog.
删除文件data1中包含字符串"3 the"的行
[root@zutuanxue ~]# sed '/3 the/d' data1
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.
文件内容查看,将文件内容输出到屏幕,使用命令p。
演示案例
打印data1文件内容
[root@zutuanxue ~]# sed 'p' data1
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.
打印data1文件第三行的内容
[root@zutuanxue ~]# sed '3p' data1
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.
打印data1文件第二、三、四行内容
[root@zutuanxue ~]# sed '2,4p' data1
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.
打印data1文件包含字符串"3 the"的行
[root@zutuanxue ~]# sed '/3 the/p' data1
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.
可以看得出,打印内容是重复的行,原因是打印了指定文件内容一次,又将读入缓存的所有数据打印了一次,所以会看到这样的效果,
如果不想看到这样的结果,可以加命令选项-n抑制内存输出即可。
2.2)命令选项说明
sed语法
在sed命令中,命令选项是对sed中的命令的增强
在命令行中使用多个命令 -e
将brown替换为green dog替换为cat
[root@zutuanxue ~]# sed -e 's/brown/green/;s/dog/cat/' data1
1 the quick green fox jumps over the lazy cat.
2 the quick green fox jumps over the lazy cat.
3 the quick green fox jumps over the lazy cat.
4 the quick green fox jumps over the lazy cat.
5 the quick green fox jumps over the lazy cat.
从文件读取编辑器命令 -f 适用于日常重复执行的场景
1)将命令写入文件
[root@zutuanxue ~]# vim abc
s/brown/green/
s/dog/cat/
s/fox/elephant/
2)使用-f命令选项调用命令文件
[root@zutuanxue ~]# sed -f abc data1
1 the quick green elephant jumps over the lazy cat.
2 the quick green elephant jumps over the lazy cat.
3 the quick green elephant jumps over the lazy cat.
4 the quick green elephant jumps over the lazy cat.
5 the quick green elephant jumps over the lazy cat.
抑制内存输出 -n
打印data1文件的第二行到最后一行内容 $最后的意思
[root@zutuanxue ~]# sed -n '2,$p' data1
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.
使用正则表达式 -r
打印data1中以字符串"3 the"开头的行内容
[root@zutuanxue ~]# sed -n -r '/^(3 the)/p' data1
3 the quick brown fox jumps over the lazy dog.
从上述的演示中,大家可以看出,数据处理只是在缓存中完成的,并没有实际修改文件内容,如果需要修改文件内容可以直接使用-i命令选项。在这里我需要说明的是-i是一个不可逆的操作,一旦修改,如果想复原就很困难,几乎不可能,所以建议大家在操作的时候可以备份一下源文件。-i命令选项提供了备份功能,比如参数使用-i.bak,那么在修改源文件的同时会先备份一个以.bak结尾的源文件,然后再进行修改操作。
1)查看文件列表,没有发现data1.bak
[root@zutuanxue ~]# ls
abc apache data1 Dobby file node-v10.14.1 Python-3.7.1 soft1 vimset
2)执行替换命令并修改文件
[root@zutuanxue ~]# sed -i.bak 's/brown/green/' data1
3)发现文件夹中多了一个data1.bak文件
[root@zutuanxue ~]# ls
abc data1 Dobby node-v10.14.1 soft1
apache data1.bak file Python-3.7.1 vimset
4)打印比较一下,发现data1已经被修改,data1.bak是源文件的备份。
[root@zutuanxue ~]# cat data1
1 the quick green fox jumps over the lazy dog.
2 the quick green fox jumps over the lazy dog.
3 the quick green fox jumps over the lazy dog.
4 the quick green fox jumps over the lazy dog.
5 the quick green fox jumps over the lazy dog.
[root@zutuanxue ~]# cat data1.bak
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.
2.3)标志
在sed命令中,标志是对sed中的内部命令做补充说明
演示文档
[root@zutuanxue ~]# cat data2
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
数字标志:此标志是一个非零正数,默认情况下,执行替换的时候,如果一行中有多个符合的字符串,如果没有标志位定义,那么只会替换第一个字符串,其他的就被忽略掉了,为了能精确替换,可以使用数字位做定义。
替换一行中的第二处dog为cat
[root@zutuanxue ~]# sed 's/dog/cat/2' data2
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
g标志:将一行中的所有符合的字符串全部执行替换
将data1文件中的所有dog替换为cat
[root@zutuanxue ~]# sed 's/dog/cat/g' data2
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
p标志:打印文本内容,类似于-p命令选项
[root@zutuanxue ~]# sed '3s/dog/cat/p' data2
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
w filename标志:将修改的内容存入filename文件中
[root@zutuanxue ~]# sed '3s/dog/cat/w text' data2
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
可以看出,将修改的第三行内容存在了text文件中
[root@zutuanxue ~]# cat text
3 the quick brown fox jumps over the lazy cat . dog
三、练习案例
3.1、写一个初始化系统的脚本
案例需求
1)自动修改主机名(如:ip是192.168.0.88,则主机名改为server88.zutuanxue.cc)
a. 更改文件非交互式 sed
/etc/sysconfig/network
b.将本主机的IP截取出来赋值给一个变量ip;再然后将ip变量里以.分割的最后一位赋值给另一个变量ip1
2)自动配置可用的yum源
3)自动关闭防火墙和selinux
1、关闭防火墙
2、关闭selinux
3、配置yum源
4、ntp时间服务器
5、更新系统软件包
3.2、写一个搭建ftp服务的脚本,要求如下:
案例需求
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"