Shell Programming and Scripting

Hello.

grep v2.21
Debian 8

I wish to search for and output these patterns in order;

Code:

"From " "To: " "Subject: " "Message-Id: " "Date: " "To: "

grep works, but not in strict order...

Code:

$ grep -a -E "^From |^Subject:|^From: |^Message-Id: |^Date: |^To: " Inbox

Result;

Code:

From - Wed Feb 18 17:18:31 2015
Subject: Re: Ram pictures
From: "Jonathan @ The Verge " <leasing@theverge.org>
Message-Id: <C9D1D4Z269-D35C-476D-8B5C@aol.com>
Date: Wed, 11 Feb 2015 20:20:31 -0800
To: deejai <Kris@sansibarr.com>

Problem 1;
The 'order' of the patterns may occur differently.
I wish to search each record ("^From " to the next "^From ")
and display the patterns in search order, then on to the next message (^From ").

Problem 2;
I can't get grep or awk to output the multiple pattern returned on one line seperated by a tab.

Problem 3;
If one of the patterns doesn't match, can a string "Blank" be used as a result ?

Desired Result;

Code:

From - Wed Feb 18 17:18:31 2015 <tab> From: howday <howday@netcom.com> Subject: Testing <tab> Message-Id: 20952083209 <tab> Date: Date: Tue, 17 Feb 2015 20:31:12 -0800 <tab> To: "better@joomz.org" <better@joomz.org>

Question;
Can this be done all in grep or awk or a combination of both?

I have tried and so far am stuck, any help would be much appreciated.

I also tried...,

Code:

awk '/^From / || /^Subject: / || /^From: / || /^Message-Id: / ||  /^Date: / || /^To: /' Inbox

looks like it's not displaying 'in order'

Thank you.

The order depends on how the sender put the lines. Try

Code:

awk '
BEGIN           {for (MX=i=split ("From To: Subject: Message-ID: Date:", KEYS); i>0; i--) VALS[KEYS[i]]
                }

function prtit()        {printf "\n"
                         for (i=1; i<=MX; i++) print VALS[KEYS[i]]
                        }

$1 in VALS      {if ($1==KEYS[1] && NR>1) prtit()
                 VALS[$1]=$0}

END             {prtit()}
' /home/...default/Mail/Local\ Folders/Inbox

Hi DSommers,
With the excellent starting point RudiC provided, can you show us how you might modify it to address your Problems 2 & 3?

RudiC, Don. I appreciate your help. Sorry to 'not' mention I wish to achieve my objective on a single line if at all possible. Thank you again. If this isn't possible, I'll pass for now. Cheers.

Not sure I understand. Is your request satisfied, and are you happy with it? Or not, and if so, are you going to improve the proposal, or do you expect us to do so?

First: you can write almost any awk script in one line. For anything this complex, however, I would never do that. I will take readable (and maintainable) over single-line every time.

Second: RudiC gave you a good starting point to reach your goal. If you are playing a game to see if you can get volunteers from the UNIX and Linux Forum to write code for you (with increasing complex requirements as the thread goes on), that isn't what we're here for. We want to help you learn how to write your own code; not act as your unpaid programming staff.

Third: Your requirements are confusing and inconsistent. First you say: Note that "From: " is not in this list. Note that "To: " is in this list twice. Then you say that the output your want is:
which has output in the order:

Code:

"From " "From: " "Subject: " "Message-ID: " "Date: Date: " "To: "

I could assume that the 1st "To: " from the 1st quote above was a typo and that "From: " was the intended header. But, why is "Date: Date: " expected to be part of your output. And, where is there just a <space> between the From: data and the Subject: data instead of <space><tab><space> that you apparently want between the other fields? Why do you want <space><tab><space> separators between fields instead of just a <tab>?

Then you say: But, you don't show us any example of what that should look like in the output. If, for example, there is no Subject: line in a mail message, are you hoping to get: Subject: "Blank", Subject: Blank, "Blank", or Blank for the Subject: section in your output?

Please take the suggestion RudiC provided and try to modify it to meet your requirements. If you run into problems, show us what you have tried and explain where you are stuck, and we'll be happy to help you. Remember to use CODE tags when presenting sample input, output, and code segments. And, be aware that if you present a single-line attempt to solve this problem, it will make it much harder (and less likely) for us to see the structure of your code, to understand the logic behind your attempt to solve your problem, and for us to figure out what needs to be fixed to turn code that doesn't quite do what you want into code that does exactly what you want.

Don, understood. Thank you for your help. Take care.
Cheers.

[SOLVED]