Hi monks,

I would like to know how to delete a line and the next line if they occur in order.

As in Assume

First line is cat

second line is dog.

If cat is followed by dog in the preceding line, I want to delete both lines.

But if dog is followed by cat, I want to keep both the lines.

for instance if input file (input.txt) has 
dog
cat 
dog
dog
cat
goat

[download]
the output file (output.txt) will be will be 
dog
dog
cat
goat

[download]
I think I should buffer some lines, but I am not sure how to proceed. Any help will be greately appreciated.

In reply to If line is followed by line, delete both lines by Ganesh Bharadwaj1

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