linux - 匹配两行，替换为三行

Question

我需要使用 sed 将 every 匹配的两行模式替换为三行模式。这是我的输入文件 (tempfile.txt)。

lease 192.168.6.100 {
  binding state free;
  hardware ethernet 00:e0:4c:68:00:96;
}
lease 192.168.6.100 {
  binding state active;
  hardware ethernet 00:e0:4c:68:00:96;
  client-hostname "andrew-H81M-S2PH";
}
lease 192.168.6.100 {
  binding state free;
  hardware ethernet 00:e0:4c:68:00:96;
}
lease 192.168.6.100 {
  binding state active;
  hardware ethernet 00:e0:4c:68:00:96;
  client-hostname "andrew-H81M-S2PH";
}

基本上，如果 client-hostname "HOSTNAME"; 缺少，则应将其替换为 tab，然后是 newline。

我的尝试:sed 'N;/硬件。*}/d; ; D'临时文件.txt

结果是:

lease 192.168.6.100 {
  binding state free;
lease 192.168.6.100 {
  binding state active;
  hardware ethernet 00:e0:4c:68:00:96;
  client-hostname "andrew-H81M-S2PH";
}
lease 192.168.6.100 {
  binding state free;
lease 192.168.6.100 {
  binding state active;
  hardware ethernet 00:e0:4c:68:00:96;
  client-hostname "andrew-H81M-S2PH";
}

这是我想要的输出。

lease 192.168.6.100 {
  binding state free;
  hardware ethernet 00:e0:4c:68:00:96;
  <tab>
}
lease 192.168.6.100 {
  binding state active;
  hardware ethernet 00:e0:4c:68:00:96;
  client-hostname "andrew-H81M-S2PH";
}
lease 192.168.6.100 {
  binding state free;
  hardware ethernet 00:e0:4c:68:00:96;
  <tab>
}
lease 192.168.6.100 {
  binding state active;
  hardware ethernet 00:e0:4c:68:00:96;
  client-hostname "andrew-H81M-S2PH";
}

如您所见， curl 之间始终存在三条线。这就是我的目标。

Answer 1

这就是诀窍(通过管道传输到 cat -A 以显示不可打印的字符):

$ sed -r 'N;s/^([[:space:]]*hardware.*)(\n})$/\1\n\t\2/;t;P;D' infile | cat -A
lease 192.168.6.100 {$
  binding state free;$
  hardware ethernet 00:e0:4c:68:00:96;$
^I$
}$
lease 192.168.6.100 {$
  binding state active;$
  hardware ethernet 00:e0:4c:68:00:96;$
  client-hostname "andrew-H81M-S2PH";$
}$
lease 192.168.6.100 {$
  binding state free;$
  hardware ethernet 00:e0:4c:68:00:96;$
^I$
}$
lease 192.168.6.100 {$
  binding state active;$
  hardware ethernet 00:e0:4c:68:00:96;$
  client-hostname "andrew-H81M-S2PH";$
}$

这不是删除匹配项，而是捕获应该围绕空行的两行并替换为换行符和制表符。我还添加了一些 anchor 以进行更安全的匹配。

这里涉及到一些技巧，因为模式空间在替换后包含两个换行符，但是 P;D 只打印第一行并开始一个新的循环，这也会导致不需要的换行符在包含 client-hostname 的行之后。

更详细的解释:

N       # Append next line to pattern space

# If the hostname is missing, insert a newline and a tab
s/^([[:space:]]*hardware.*)(\n})$/\1\n\t\2/

t      # If we did the substitution, jump to end (prints complete pattern space)
P      # Print first line in pattern space
D      # Delete first line in pattern space - starts new cycle