使这个 sed 脚本与一个而不是另一个的这两对字符串有什么不同？

Question

这个问题与我今天早些时候提出的另一个问题有关：

我有一个这样的文本文件

I want= to keep this
        This is some <text> I want to keep <and "something" in tags that I" want to keep> aff FOO1 WebServices and some more "text" that" should "</be> </deleted>
        <this is stuff in tags I want=to begone> and other text I want gone too. </this is stuff in tags I want to begone> 
       A novice programmer walked into a "BAR2" descript keepthis
        and this even more text, let's keep it
    <I actually want this>
    and this= too.`

当我使用 sed -f script.sed file.txt 到运行这个脚本时：

# Check for "aff"
/\baff\b/    {   
# Define a label "a"
:a  
# If the line does not contain "desc"
/\bdesc\b/!{
# Get the next line of input and append
    # it to the pattern buffer
    N
    # Branch back to label "a"
    ba
}   
# Replace everything between aff and desc
s/\(\baff\)\b.*\b\(desc\b\)/TEST DATA/
}

我得到这个作为我的输出：

       I want= to keep this
        This is some <text> I want to keep <and "something" in tags that I" want to keep> aff FOO1 WebServices and some more "text" that" should "</be> </deleted>
        <this is stuff in tags I want=to begone> and other text I want gone too. </this is stuff in tags I want to begone> 
       A novice programmer walked into a "BAR2" descript keepthis
        and this even more text, let's keep it
    <I actually want this>
    and this= too.

但是，只需将搜索字符串从 aff 和 desc 更改为 FOO1 和 BAR2：

   # Check for "FOO1"
/\bFOO1\b/    {   
# Define a label "a"
:a  
# If the line does not contain "BAR2"
/\bBAR2\b/!{
# Get the next line of input and append
    # it to the pattern buffer
    N
    # Branch back to label "a"
    ba
}   
# Replace everything between FOO1 and BAR2
s/\(\bFOO1\)\b.*\b\(BAR2\b\)/TEST DATA/
}

给出预期的输出：

I want= to keep this
This is some <text> I want to keep <and "something" in tags that I" want to keep> aff FOO1TEST DATABAR2" descript keepthis
    and this even more text, let's keep it
<I actually want this>
and this= too.`

我完全不知道这里发生了什么。为什么在 FOO1 和 BAR2 之间搜索的工作方式与使用 aff 和 desc 的完全相同的脚本不同？

Answer 1

结束标记应为 \bdesc 而不是 \bdesc\b。

注意模式中的 \b，它匹配 word boundary。您上面的文字包含单词 description，但不包含 desc。

你之前的问题让我假设你想要那个。如果您不关心单词边界，请完全删除 \b 转义序列。

使这个 sed 脚本与一个而不是另一个的这两对字符串有什么不同？

What is different about these two pairs of strings that makes this sed script with one and not the other?

string

sed

scripting

multiline