regex - 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内容为:

# 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 

but it is replacing at only one place.

# 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
}

让它在两个地方都工作的正确命令是什么？

注意:我可以将 disable = yes 替换为 disable = no 而无需匹配 service chargen 但我需要使用相同的 sed/perl 命令替换 /etc/xinetd.conf 中也将有其他服务。

更新 正如 Jonathan 在他的评论中强调的那样，disable 可以在花括号内的任何位置。

Answer 1

使用 sed，您可以使用:

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

第一部分搜索从service chargen开始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 且 disable 和 = yes 之间有任意数量空格的行，并更改 yes 到 no。如有必要，您可以使正则表达式更加复杂(没有尾随空格；不要编辑 service chargen2018 block ，要求 } 没有尾随空格，等等)但它可能没有必要。

您通常可以进行就地编辑，但要注意系统之间在执行方式语义方面的差异。 (BSD和macOS需要-i ''；GNU只需要-i；都接受-i.bak，两者意思相同— 但你有一个备份文件要清理。)