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Asked: 2017-12-15 04:44:45 +0800 CST

sed -l option for line-wrapping is not working

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sed -e 's/word1/word2/' -l 3 output > output2

I'm testing this command. I expected 3 characters for each line. But, it doesn't work. output2 has the same line breaks as output. Have I misunderstand line-wrapping??

command-line

1 Answers

  1. Best Answer

    In short... yes you have misunderstood line-wrapping slightly ;)

    -l N, --line-length=N
       specify the desired line-wrap length for the `l' command

    So, it only works with the l command:

    l      List out the current line in a ``visually unambiguous'' form.
l width
       List out the current line in a ``visually unambiguous'' form,
       breaking it at width characters.  This is a GNU extension.

    If you want the output three characters per line, you could use this:

    sed -nl 4 's/word1/word2/;l' output > output2

    or this in GNU sed:

    sed -n 's/word1/word2/;l 4' output > output2

    Note that a trailing backslash (to escape the line break) is appended if there is not actually a new line (end-of-line is indicated by $ characters). We need to use the -n flag, because the l command is for viewing rather than editing, like the = command, and the line will appear as normal after l has output it in the requested form, unless suppressed by -n.

    You might get more like what you actually want by simply breaking the file after every three characters:

    sed 's/word1/word2/; s/.../&\n/g' output > output2

    or to split after, say, 10 characters:

    sed -r 's/word1/word2/; s/.{10}/&\n/g' output > output2
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