如何从文件中提取多行扩展的电子邮件标题 [英] How to extract email headers extending on multiple lines from file

问题描述

我正在尝试在Linux上使用sed从电子邮件文件中提取To标头.

I am trying to extract the To header from an email file using sed on linux.

问题在于To标头可能在多行上.

The problem is that the To header could be on multiple lines.

例如:

To: [e-mail], [e-mail],
    [e-mail], [e-mail], 
    [e-mail]
Message-ID: <[e-mail]>

我尝试了以下操作:

sed -n -e '/^[Tt]o: / { N; p; }' _message_file_ |
    awk '{$1=$1;printf("%s ",$0)};NR%2==0{print ""}'

sed命令提取以To和下一行开头的行. 我将输出通过管道传输到awk，以将所有内容都放在一行中.

The sed command extracts the line starting with To and next line. I pipe the output to awk to put everything on a single line.

完整命令在一行中输出:

The full command outputs in one line:

To: [e-mail], [e-mail], [e-mail], [e-mail]

我不知道如何继续测试下一行是否以空格开头并将其添加到结果中.

I don't know how to keep going and test if the next line starts with whitespace and add it to the result.

我想要的是所有地址

To: [e-mail], [e-mail], [e-mail], [e-mail], [e-mail]

任何帮助将不胜感激.

推荐答案

formail是一个很好的解决方案，但以下是使用sed的方法:

formail is a good solution but here's how to do it with sed:

sed -e '/^$/q;/^To:/!d;n;:c;/^\s/!d;n;bc' message_file 

• /^$/q;-(可选)如果标头用尽，则退出
• /^To:/!d;-如果不是To:标头，则停止处理此行
• n;-否则，隐式打印它并加载下一行
• :c;-c是我们可以分支到的标签
• /^\s/!d;-如果不是继续，请停止处理此行
• n;-否则，隐式打印它并加载下一行
• bc-分支回到标签c(即循环)
• /^$/q; - (optional) quit if we run out of headers
• /^To:/!d; - if not a To: header, stop processing this line
• n; - otherwise, implicitly print it, and load next line
• :c; - c is a label we can branch to
• /^\s/!d; - if not a contination, stop processing this line
• n; - otherwise, implicitly print it, and load next line
• bc - branch back to label c (ie. loop)

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