如何在 BSD 上的 csh 中使用 sed 将一行替换为两行？

Question

我这里有一个非常简单的文本文件，其中包含以下内容

line1
line2
line3
line4

我想通过 sed（或其他一些应用程序）修改内容，所以它变成

line1
line2
#this line was added by sed
line3
line4

所以我尝试了sed -e "s/line2/line2\\n#this line was added by sed/" my-text-file-here.txt，但输出是：

line1
line2\n#this line was added by sed
line3
line4

关于如何正确执行的任何想法？谢谢

Answer 1

使用 GNU sed，您的代码可以正常工作：

$ sed -e 's/line2/line2\n#this line was added by sed/' file
line1
line2
#this line was added by sed
line3
line4

然而，对于 BSD sed，\n在替换文本中不被视为换行符。如果您的 shell 是 bash，一个好的解决方法是$'...'插入换行符：

$ sed -e $'s/line2/line2\\\n#this line was added by sed/' file
line1
line2
#this line was added by sed
line3
line4

除了bash之外，zsh和ksh也支持$'...'。

另一种选择是插入真正的换行符：

$ sed -e 's/line2/line2\
#this line was added by sed/' file
line1
line2
#this line was added by sed
line3
line4

更新：在 csh 中，最后一个选项需要额外的\：

% sed -e 's/line2/line2\\
#this line was added by sed/' file
line1
line2
#this line was added by sed
line3
line4

Answer 2

看起来你想要A确实是pend命令。使用 Bash 或任何支持的 shell $'\n'（大多数都支持）：

sed $'/line2/a\\\n#this line was added by sed\n' file.txt

或者，更易读的是，使用 sed 命令文件：

/line2/a\
#this line was added by sed

显示完整方法：

$ cat file.txt 
line1
line2
line3
line4
$ cat sedfile 
/line2/a\
#this line was added by sed
$ sed -f sedfile file.txt 
line1
line2
#this line was added by sed
line3
line4
$ 

Answer 3

这是假设csh外壳：

简单地追加一行又一行：

% sed '/line2/a\\
# new line here\
' file
line1
line2
# new line here
line3
line4

要在另一行之前插入一行：

% sed '/line3/i\\
# new line here\
' file
line1
line2
# new line here
line3
line4

要使用以下命令用两个新行替换一行s：

% sed 's/line2/&\\
# new line here/' file
line1
line2
# new line here
line3
line4

在 OpenBSD 6.1 上运行sed并csh在基本系统上进行了测试。