SED，awk.grep - 添加一行到配置节结束时，如果该行不存在 [英] sed,awk.grep - add a line to the end of a configuration section if the line doesn't already exist

问题描述

我想用SED / AWK编辑一个文件。该文件是由一些配置，如：

I want to edit a file using sed/awk. The file is made up of several configuration sections, like this:

SECTION 1 BEGIN
some stuff
SECTION END

SECTION 2 BEGIN
some stuff
some more stuff
important line
SECTION END

我想重要的行添加到第2部分，如果它不存在，$结束p $ pferably作为命令单行。我一直在寻找的比fgrep / sed的组合<一个href=\"http://stackoverflow.com/questions/9118553/add-a-line-to-a-file-section-unless-it-exists?answertab=active#tab-top\">in这个问题，但我不太明白如何适应它我需要什么。

I want to add important line to the end of SECTION 2 if it doesn't already exist, preferably as a command one liner. I've been looking at the fgrep/sed combo in this question, but I don't quite understand how to adapt it for what I need.

注：有可能在部分空行

非常感谢。

推荐答案

使用 AWK ：

awk '
  $0 == "SECTION 2 BEGIN" { inSec2 = 1 } 
  inSec2 && $0 == "important line" { hasImportant = 1 } 
  inSec2 && $0 == "SECTION END" { 
    if (!hasImportant) { print "important line" } 
    inSec2 = 0
  }
  1'

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