bash - 使用 sed 处理一段完整的文本

Question

我是第一次尝试 bash 脚本，但我一直坚持使用 sed更改配置文件。我需要编辑的键是非常通用的并且在整个文件中使用，所以我必须依靠一个部分来知道在哪里做我的“触摸”。

因此，如前所述，文件周围有多个部分，由 [section name] 声明然后在它下面，你有该部分的配置，由一个标签缩进。有像 enabled 这样的键, type等在整个文件中使用。

所以一个完整的部分看起来像这样:

[backend]
        # enabled = no
        # data source = average
        # type = graphite
        # destination = localhost
        # prefix = netdata
        # hostname = localhost
        # update every = 10
        # buffer on failures = 10
        # timeout ms = 20000

所以我需要做的是:

取消注释整个部分

更改enabled = no至enabled = yes

更改destination的值到带有端口的 IP 地址 ( 192.168.99.38:2003 )

更改hostname的值到另一个主机名，可能是机器的主机名($HOSTNAME？)。

问题是，我根本不知道如何解决这个问题。我四处寻找 sed 多行处理，但我绝对不知道如何匹配 [backend]仅限部分。这对我来说很新鲜。

Answer 1

As you comment me: Only what's under [backend], nothing else

您可能会对 这样做感兴趣Perl 如果 不是 只是评论我;我将删除和答案。

假设你有这个文件:

[no-backend]
        # enabled = no
        # data source = average
        # type = graphite
        # destination = localhost
        # prefix = netdata
        # hostname = localhost
        # update every = 10
        # buffer on failures = 10
        # timeout ms = 20000

[backend]
        # enabled = no
        # data source = average
        # type = graphite
        # destination = localhost
        # prefix = netdata
        # hostname = localhost
        # update every = 10
        # buffer on failures = 10
        # timeout ms = 20000

[no-backend]
        # enabled = no
        # data source = average
        # type = graphite
        # destination = localhost
        # prefix = netdata
        # hostname = localhost
        # update every = 10
        # buffer on failures = 10
        # timeout ms = 20000  

这个单行代码会为您找到该部分:

perl  -lne '$b=$.; $e=($b+10) if /\[backend\]/;print if $b++<$e' file

or readable version
perl -lne 'if( /\[backend\]/ ){ $b=$.; $e=( $b+10 ); }; if( $b++ < $e ){ print }' file

和输出:

[backend]
        # enabled = no
        # data source = average
        # type = graphite
        # destination = localhost
        # prefix = netdata
        # hostname = localhost
        # update every = 10
        # buffer on failures = 10
        # timeout ms = 20000

现在而不是 打印 您可以修改该部分:

s/#//;s/no/yes/;s/(?<=destination = ).+$/192.168.99.38:2003/;s/(?<=hostname = ).+$/$HOSTNAME/

完整的单行

perl -lpe 'if(/\[backend\]/){$b=$.;$e=($b+10);};if($b++<$e){ s/#//;s/no/yes/;s/(?<=destination = ).+$/192.168.99.38:2003/;s/(?<=hostname = ).+$/\$HOSTNAME/ }' file

和输出:

[no-backend]
        # enabled = no
        # data source = average
        # type = graphite
        # destination = localhost
        # prefix = netdata
        # hostname = localhost
        # update every = 10
        # buffer on failures = 10
        # timeout ms = 20000
[backend]
         enabled = yes
         data source = average
         type = graphite
         destination = 192.168.99.38:2003
         prefix = netdata
         hostname = $HOSTNAME
         update every = 10
         buffer on failures = 10
         timeout ms = 20000

[no-backend]
        # enabled = no
        # data source = average
        # type = graphite
        # destination = localhost
        # prefix = netdata
        # hostname = localhost
        # update every = 10
        # buffer on failures = 10
        # timeout ms = 20000

最后在检查输出是否一切正常后，您可以使用 -i使用就地编辑功能的选项，例如:
perl -i.bak -lne '...the rest of the script...' file
.bak 仅用于备份旧文件。 (如:file.txt.bak)

更新 为您的评论

perl -lpe '$hn=qx(cat /etc/hostname);chomp $hn;if(/\[backend\]/){$b=$.;$e=($b+10);};if($b++<$e){s/#//;s/no/yes/;s/(?<=destination = ).+$/192.168.99.38:2003/;s/(?<=hostname = ).+$/$hn/ }' file  

和输出:

...
...
[backend]
         enabled = yes
         data source = average
         type = graphite
         destination = 192.168.99.38:2003
         prefix = netdata
         hostname = k-five
         update every = 10
         buffer on failures = 10
         timeout ms = 20000
...
...