Re: lines matching N and N+1

On Mon, 28 Jan 2013 20:18:23 -0000, "Daniel" <[email protected]> wrote:

> This came up in a recent cross-Atlantic conversation. :)
> 
> The problem: How to apply a change when a *combination* 
> of lines occurs, eg when the word "foo" appears in line 
> N and the word "bar" appears in line N+1. How then to 
> apply the change in line N (or line N+1)? For example, 
> change word "foo" to "FOO" and word "bar" to "BAR".
> 
> Here's a test file I dreamed up:
> 
> food foot foo
> bare bark bar
> bar bark bare
> bark bar bare
> foot foo food
> bark bar bare
> foot foo food
> foo foot food
> bar bark bare
> foot foo food 
> 
> Here's the desired output:
> 
> food foot FOO
> bare bark BAR
> bar bark bare
> bark bar bare
> foot FOO food
> bark BAR bare
> foot foo food
> FOO foot food
> BAR bark bare
> foot foo food 
> 
> I tried doing this in bash and couldn't make it
> work. I do have a possible sed solution.
> 
> Thought I'd post this, see if anyone would like
> to take a look, either sed or bash (or whatever!).

I assume that you use "word" as meant by GNU sed's \< and \> operators (or
\b). Leaving out some unspecified corner cases:

$!N
s/\<foo\>\(.*\n.*\)\<bar\>/FOO\1BAR/
P
D

If "foo" and "bar" are regular expressions and not fixed strings, turning
them to uppercase is more complicated, yet still possible using GNU sed
(which I'm assuming anyway);

$!N
s/\(\<foo\>\)\(.*\n.*\)\(\<bar\>\)/\U\1\E\2\U\3\E/
P
D


-- 
D.