removing line breaks, and operating on an entire stream

[ansient]

Suppose I have a file with the following:

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key1
value1
key2
value2
key3
value3
...

And I want to change this to:

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key1	value1
key2	value2
key3	value3
...

Is there an easy way to do this with bash/sed/awk?

Secondly, is there a way to do something like:

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sed 's/....\n..../.....foo..../g'

And have it operate on the entire stream instead of line-by-line?

[karnesky]

If the key and value are differentiated in some way, just improve your matching expression. If they aren't, but they are always on every other line, make a shell script which loops over every line & has different behavior for odd and even lines.

[ansient]

If the key and value are differentiated in some way, just improve your matching expression.

I can easily match either a particular key or a value, but how can I match both at once in order to output them on the same line?

If they aren't, but they are always on every other line, make a shell script which loops over every line & has different behavior for odd and even lines.

So...

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#!/bin/bash
declare lastline
declare count=1;
while read line; do
    if [ $(($count % 2)) = 0 ]; then
        echo -e "$lastline\t$line"
    fi
    let $((count++));
    lastline="${line}";
done < $@

Is that really the best way?

[TrueDFX]

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while read line1
do
    read line2
    printf '%s\t%s\n' "$line1" "$line2"
done

Is that close enough to what you want?

Or

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sed 'N;s/\n/\t/'

Secondly, is there a way to do something like:

Code: Select all

sed 's/....\n..../.....foo..../g'

And have it operate on the entire stream instead of line-by-line?

Code: Select all

sed -e '
    :start
# after the last line is read in, go to the part where you can modify your text
    $bmodify
# otherwise, read in the next line
    N
# and go back (until the whole file is read)
    bstart
# here, the whole file is in memory
    :modify
# so you can search/replace things like this
    s/A\nB/replaced/g
'

But, there almost always is a nicer way which won't suddenly fail if files get too big.