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How can I match whitespace in sed? In my data I want to match all of 3+ subsequent whitespace characters (tab space) and replace them by 2 spaces. How can this be done?

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2 Answers

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The character class \s will match the whitespace characters <tab> and <space>.

For example:

$ sed -e "s/\s\{3,\}/  /g" inputFile

will substitute every sequence of at least 3 whitespaces with two spaces.

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aha! It was the missing -e switch that got me. – sequoia mcdowell Sep 12 '11 at 14:44
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I also had to add '-r' switch which enables extended regex's to make sed recognize '\s' as space. – HUB May 16 '12 at 15:12
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Some older versions of sed may not recognize \s as a white space matching token. In that case you can match a sequence of one or more spaces and tabs with '[XZ][XZ]*' where X is a space and Z is a tab.

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So for the particular need here, with an older sed, you could do: $ sed 's/[XZ][XZ][XZ][XZ]*/ /g' inputfile where X is a tab and Z is a space. – Marnix A. van Ammers Apr 12 '10 at 15:08

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