perl命令：批量修改替換文件

需求以下：有nginx負載均衡配置文件，更新某幾臺服務器須要先註釋掉前端機器，須要用腳本實現；

以前一直用sed進行替換，遇到一個高手用perl命令也能夠實現，命令更簡潔直觀，能夠實現一樣的效果。

舉例以下：

[root@localhost ~]# cat host.conf

upstream test_server {

server   192.168.169.36:80;

server   192.168.169.37:80;

server   192.168.169.38:80;

server   192.168.169.39:80;

server   192.168.169.50:80;

server   192.168.169.51:80;

server   192.168.169.52:80;

}

打印匹配的行

[root@localhost ~]# perl -ne 'print if /192.168.169.3/' host.conf

server   192.168.169.36:80;

server   192.168.169.37:80;

server   192.168.169.38:80;

server   192.168.169.39:80;

[root@localhost ~]# perl -ne 'print if /192.168.169.5/' host.conf

server   192.168.169.50:80;

server   192.168.169.51:80;

server   192.168.169.52:80;

perl命令：匹配192.168.169.3 網段的前面加#；

-i 寫入到文件

[root@localhost ~]# perl -i -pe 's/(.*)/#$1/ if /192.168.169.3/' host.conf

執行結果以下：

[root@localhost ~]# cat host.conf

upstream test_server {

#server   192.168.169.36:80;

#server   192.168.169.37:80;

#server   192.168.169.38:80;

#server   192.168.169.39:80;

server   192.168.169.50:80;

server   192.168.169.51:80;

server   192.168.169.52:80;

}

同理，去掉#

[root@localhost ~]# perl -i -pe 's/#(.*)/$1/ if /192.168.169.3/' host.conf

[root@localhost ~]# cat host.conf

upstream test_server {

server   192.168.169.36:80;

server   192.168.169.37:80;

server   192.168.169.38:80;

server   192.168.169.39:80;

server   192.168.169.50:80;

server   192.168.169.51:80;

server   192.168.169.52:80;

}

匹配192.168.169. 網段的全部機器加#

[root@localhost ~]# perl -i -pe 's/(.*)/#$1/ if /192.168.169./' host.conf

[root@localhost ~]# cat host.conf

upstream test_server {

#server   192.168.169.36:80;

#server   192.168.169.37:80;

#server   192.168.169.38:80;

#server   192.168.169.39:80;

#server   192.168.169.50:80;

#server   192.168.169.51:80;

#server   192.168.169.52:80;

}

perl命令也支持相似sed的關鍵字替換

[root@localhost ~]#  perl -pe 's/server/master/ if /192.168.169.3/' host.conf

upstream test_server {

master   192.168.169.36:80;

master   192.168.169.37:80;

master   192.168.169.38:80;

master   192.168.169.39:80;

server   192.168.169.50:80;

server   192.168.169.51:80;

server   192.168.169.52:80;

}

問題來了，實際配置文件基本都是同一個網段的ip，若是匹配的話，會匹配到其餘機器上面，問題就嚴重了，因此須要按指定行進行精確匹配；

[root@localhost ~]# cat host.conf

upstream test_server {

server   192.168.169.36:80;

server   192.168.169.37:80;

server   192.168.169.38:80;

server   192.168.169.39:80;

server   192.168.169.50:80;

server   192.168.169.51:80;

server   192.168.169.52:80;

}

perl命令，匹配指定的行

if 判斷 $. 行數，與或關係進行匹配；

[root@localhost ~]#  perl -ne 'print if $.==2 ' host.conf

server   192.168.169.36:80;

[root@localhost ~]#  perl -ne 'print if $.==4 ' host.conf

server   192.168.169.38:80;

[root@localhost ~]#  perl -ne 'print if $.>=2 && $.<=5 ' host.conf

server   192.168.169.36:80;

server   192.168.169.37:80;

server   192.168.169.38:80;

server   192.168.169.39:80;

精確匹配，進行替換，大於等於第2行，小於等於第5行；

[root@localhost ~]# perl -pe 's/(.*)/#$1/ if $.>=2 && $.<=5' host.conf

upstream nav1_server {

#server   192.168.169.36:80;

#server   192.168.169.37:80;

#server   192.168.169.38:80;

#server   192.168.169.39:80;

server   192.168.169.50:80;

server   192.168.169.51:80;

server   192.168.169.52:80;

}

加-i 參數，將修改的操做寫入到文件中；

[root@localhost ~]# perl -i -pe 's/(.*)/#$1/ if $.>=2 && $.<=5' host.conf