Print paragraph after matching pattern

Question

I would like to print the lines between two empty lines only after a match is made. My data looks like this:

List A
Item 1
Item 2
Item 3

Item 4
Item 5

List B
Item 1
Item 2
Item 3

Thus, I'm trying to get a sed or awk or grep command to match List A and get the output of

Item 4
Item 5

So far, I have tried doing:

sed '/^$/,/^$/!d'

and

sed '/list\sA.*^$/,/^$/!d'

In this case, I'm trying to print the range and define the first pattern as the string and everything included until the empty line.

I have also tried other code with:

awk -v RS='' -v ORS='\n\n'

But, this only gives me the paragraph that contains the pattern, I'm trying to get the paragraph after that.

Finally, I think it is something using sed -n and uses the { } with labels but I'm just not advanced enough to put it all together. Would really appreciate if you could point me in the right direction.

Not exactly, I would like to match "List A" and print the paragraph after that which would be: Item 4 Item 5 — DomainsFeatured, Jun 21 '16 at 06:39

fedorqui · Accepted Answer · 2016-06-21T06:43:12.973

4

When you match a pattern, get the next record with getline:

$ awk -v RS='' '/List A/ {getline; print}' file
Item 4
Item 5

edited Jun 21 '16 at 06:43

answered Jun 21 '16 at 06:38

fedorqui

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This works perfectly. I had to add a few things to make sure formatting was good but that is correct code. Thanks for the help! – DomainsFeatured Jun 21 '16 at 07:01
Quick follow up on this one. If I wanted to remove those two lines from the file, is there an easy way to do that using a similar awk command? – DomainsFeatured Jun 21 '16 at 07:14
1

@DomainsFeatured you want to check [awk modifications in place](http://stackoverflow.com/a/16529730/1983854). – fedorqui Jun 21 '16 at 07:41

hek2mgl · Answer 2 · 2016-06-21T06:54:45.617

I would suggest to use awk here as shown in fedorqui's answer. However, the following sed command would work as well:

sed -n '/List A/{:a;n;/^$/!ba;:b;n;/^$/!{p;bb}}' file

Explanation:

/List A/ { 
    :a          # Label "a"
    n           # Get new line from input
    /^$/! ba    # If this line is not empty jump back to :a
    :b          # Label "b"
    n           # Get new line from input
    /^$/! {     # If this line is not empty:
        p       #   Print the line
        bb      #   Jump back to :b  
    }
}

The option -n suppresses printing of lines unless p is used.

Print paragraph after matching pattern

2 Answers2