组团学

shell对文件的操作

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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

sed处理数据原理.png

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

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

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

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"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

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

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"
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