Question

I have multiple files in a folder and each of them have one email message. Each message has a header in the format

Subject: formatting fonts
To: [e-mail]
From: sender name

message body

I want to get all the unique sender names from all the messages (there is only 1 message per file) . How can I do that?

Answer 1

Assuming there can’t be random headers in the middle of the messages, then this should do the trick:

cat * | grep '^From: ' | sort -u

If there may be other misleading “From:” lines in the middle of the messages, then you just need to make sure you are only getting the first matching line from each message, like so:

for f in * ; do cat $f | grep '^From: ' | head -1 | sort -u ; done

Obviously you can replace the * in either command with a different glob or list of file names.