Question

First, I have what I believe to be a workable solution. However, test cases
are one thing …reality is not always so kind. This is a “Does this look right?”
question …or, better, “Where might this fail? Suggest improvements?” question.

Problem:

Title should not creep past one line.

Test file:

You have a hold available for pickup as of 2012-01-13:
Title: Really Long Test Title Regarding Random Gibberish. Volume 1, A-B, United States
 and affiliated territories, United Nations, countries of the world
Author: Barrel Roll Morton
Copy: 3
#end-of-record
You have a hold available for pickup as of 2012-01-13:
Title: Short Catalogue of Random Gibberish. Volume 1, A-B, United States
Author: Skippy Credenza
Copy: 12
#end-of-record

Expected output:

You have a hold available for pickup as of 2012-01-13:
Title: Really Long Test Title Regarding Random Gibberish. Volume 1, A-B, United States
Author: Barrel Roll Morton
Copy: 3
#end-of-record
You have a hold available for pickup as of 2012-01-13:
Title: Short Catalogue of Random Gibberish. Volume 1, A-B, United States
Author: Skippy Credenza
Copy: 12
#end-of-record

My solution:

sed -e '/^Title/{N;/\nAuthor:/!{s/\n.*$//}}' test-file.txt

My logic re: above proposed solution

• Look for regex /^Title/
• Grab next line
• If next line does not match /^Author/
• Then search for regex /\n.*$/
• Replace with nada.

Is there a more bullet proof way to do this?

Answer 1

That looks good, but if you don’t have control on how long that first line of text is, you can further truncate it using something like

sed '/^Title/{N;/\nAuthor:/!{s/^\(....................\).*\n.*$/\1/;};}' test-file.txt

(You don’t need the -e, but it doesn’t hurt either).

I use an old-school sed, so I need the ;};} extra-bits.

Adjust the number of ‘.’s in the match-pattern for the length of value you want to capture.

Newer sed support curly-braced ranges, something like, cut I don’t have access to confirm.

sed '/^Title/{N;/\nAuthor:/!{s/^\(.\{30,50\}\).*\n.*$/\1/;};}' test-file.txt

Edit per @JonathanLeffler ‘s comment below. fixed range notation, change 30,50 to values that work for you.

I hope this helps.