CODEWITHSUNDEEP
awksed
Craig Ringer
Craig Ringer

Reputation: 324455

How do I replace a multiline string in sed with a placement with leading spaces

I have a file with lines like

 something 
-----------

where there's a leading and trailing space after something. I want to replace it with

 other 
-------

and preserve the leading and trailing space. How?

Upvotes: 0

Views: 184

Answers (3)

Ed Morton
Ed Morton

Reputation: 203502

sed is for simple substitutions on individual lines, that is all, for anything else you should be using awk:

$ awk 'n{$0=substr($0,1,n); n=0} {sub(/^ something $/," other "); n=length()}1' file
 other
-------

That will work with any awk in any shell on any UNIX box.

Upvotes: 1

potong
potong

Reputation: 58400

This might work for you (GNU sed):

sed -i '/^ something $/{:a;N;/^--*$/M!ba;s/something/other/}' file

Gather up lines between the start and end markers, then replace the required string with the alternative.

N.B. Uses the M flag to make an exact match within multiple lines.

Upvotes: 1

Craig Ringer
Craig Ringer

Reputation: 324455

sed can match multiple lines with a comma separated set of regexps. And substitute everything in the range with the c command. To get the c command not to ignore leading white space, use a backslash after it. e.g.

sed -i.original '/^ something $/,/-----------$/c\ other \n-------' input-filename

Upvotes: 0

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