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

但它只在一个地方取代。

 # 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 } 

什么是让它在两个地方都有效的正确命令？

注意 ：我可以用disable = no替换disable = yes而不匹配service chargen但是我需要在/etc/xinetd.conf使用相同的sed / perl命令来替换其他服务。

更新正如Jonathan在评论中强调的那样，禁用可以位于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/; }'

第一部分搜索从一个起始service chargen到第一行的行的范围，然后以}开头; 在该范围内时，它查找包含线disable = yes与之间的空间任意数disable和= yes ，和改变yes对no 。 如果有必要，你可以使正则表达式更繁琐（没有尾随空格;不编辑service chargen2018块，要求}没有尾随空白等）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如何执行此操作的语义上的差异。 （BSD和macOS需要-i '' ; GNU只需要-i ;两者都接受-i.bak ，两者意味着相同 - 但你有一个备份文件要清理。）

Answer 2

您可以使用此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演示

\\K重置报告的匹配的起点。 最终匹配中不再包含任何先前消费的字符

Answer 3

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

您可以根据自己的喜好调整正则表达式（ /disable/ ）（例如/^ *disable *=/ ）。