UNIX for Dummies Questions & Answers

sed will never match a "terminal" new-line. To make it match a "terminal" new-line, you need to create a multi-line pattern space so that the "terminal" new-line of first line becomes an "embedded" new-line which can be matched by a pattern.

This was precisely the essence of alister's solution:

Code:

sed '/a/{$q; N; s/a\nb/d/;}'

At the line containing "a", execute the following series of edits:

i) check if it's the last line; if last line, quit the script.

ii) N -- read in the next line and append it to the pattern space so that the pattern space becomes "a\nb" or "a\nc" or "a\nk", etc.

iii) if pattern space consists of "a\nb", replace it with "d". The pattern space then becomes "d" or "a\nc" or "a\nk", etc.