Perl/Sed 命令多次替换相同的模式

Question

我需要使用 perl 或 sed 等命令在 /etc/xinetd.d/chargen 中设置 disable=no。

/etc/xinetd.d/chargen内容是：

# description: An xinetd internal service which generate characters.  The
# xinetd internal service which continuously generates characters until the
# connection is dropped.  The characters look something like this:
# !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefg
# This is the tcp version. 
service chargen
{
        disable         = yes
        type            = INTERNAL
        id              = chargen-stream
        socket_type     = stream
        protocol        = tcp
        user            = root
        wait            = no 
}

# This is the udp version. 
service chargen
{
        disable         = yes
        type            = INTERNAL
        id              = chargen-dgram
        socket_type     = dgram
        protocol        = udp
        user            = root
        wait            = yes 
}

我用过perl命令

perl -0777 -pe 's|(service chargen[^\^]+)disable\s+=\syes|\1disable=no|' /etc/xinetd.d/chargen 但它只在一个地方替换。

# description: An xinetd internal service which generate characters.  The
# xinetd internal service which continuously generates characters until the
# connection is dropped.  The characters look something like this:
# !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefg
# This is the tcp version.
service chargen
{
        disable         = yes
        type            = INTERNAL
        id              = chargen-stream
        socket_type     = stream
        protocol        = tcp
        user            = root
        wait            = no
}

# This is the udp version.
service chargen
{
        disable=no
        type            = INTERNAL
        id              = chargen-dgram
        socket_type     = dgram
        protocol        = udp
        user            = root
        wait            = yes
}

什么是让它在这两个地方都工作的正确命令？

注意：我可以用 disable = no 替换 disable = yes 而不匹配 service chargen 但我需要使用相同的 sed/perl 命令替换 /etc/xinetd.conf 中的其他服务.

更新正如乔纳森在他的评论中强调的那样，禁用可以在花括号内的任何位置。

Answer 1

您可以使用这个perl 命令：

perl -0777 -pe 's/(?m)^service chargen\s*\{[^}]*disable\s*=\s*\Kyes/no/g' file

# description: An xinetd internal service which generate characters.  The
# xinetd internal service which continuously generates characters until the
# connection is dropped.  The characters look something like this:
# !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefg
# This is the tcp version.
service chargen
{
        disable         = no
        type            = INTERNAL
        id              = chargen-stream
        socket_type     = stream
        protocol        = tcp
        user            = root
        wait            = no
}

# This is the udp version.
service chargen
{
        disable         = no
        type            = INTERNAL
        id              = chargen-dgram
        socket_type     = dgram
        protocol        = udp
        user            = root
        wait            = yes
}

RegEx Demo

\K 重置报告匹配的起点。任何以前消耗的字符都不再包含在最终匹配中

Answer 2

Awk 好吗？：

$ awk '/service chargen/,/}/{if(/disable/)sub(/yes/,"no")}1' file
...
        disable         = no
...
        disable         = no
...

解释：

$ awk '                          # well, awk
/service chargen/,/}/ {          # between service chargen {...}
    if(/disable/)                # if disable found
        sub(/yes/,"no")          # replace yes with no
}1' file                         # output

请随意调整正则表达式 (/disable/)，使其符合您的喜好（例如 /^ *disable *=/）。

Answer 3

使用sed，可以使用：

sed -e '/^service chargen/,/^}/ { /disable *= yes/ s/yes/no/; }'

第一部分搜索从以service chargen 开头的第一行到之后以} 开头的第一行的行范围；在该范围内，它查找包含disable = yes 的行，在disable 和= yes 之间有任意数量的空格，并将yes 更改为no。如有必要，您可以使正则表达式更加繁琐（没有尾随空格；不要编辑 service chargen2018 块，要求 } 没有尾随空格等）但可能没有必要。

您通常可以进行就地编辑，但要注意系统之间在执行此操作的语义方面的差异。 （BSD 和 macOS 需要 -i ''；GNU 只需要 -i；两者都接受 -i.bak 并且两者的含义相同——但您需要清理一个备份文件。）