Text Processing – Remove Line Containing Certain String and the Following Line

awkreplacesedtext processing

I use this

cat foo.txt | sed '/bar/d'

to remove lines containing the string bar in the file.

I would like however to remove those lines and the line directly after it. Preferably in sed, awk or other tool that's available in MinGW32.

It's a kind of reverse of what I can get in grep with -A and -B to print matching lines as well as lines before/after the matched line.

Is there any easy way to achieve it?

Best Answer

If you have GNU sed (so non-embedded Linux or Cygwin):

sed '/bar/,+1 d'

If you have bar on two consecutive lines, this will delete the second line without analyzing it. For example, if you have a 3-line file bar/bar/foo, the foo line will stay.

Related Solutions

Grep string where next line does not contain string

You can use perl compatible regular expressions grep:

$ pcregrep -M '(searchString.*\n)(?!.*excludeString)' file
foo2 searchString bar
foo3 searchString bar
foo4 searchString bar

It searches searchString followed by any char ., repeated zero or more times *, followed by new line \n only if there is not (?!) pattern .*excludeString next to it. Option -M is present in order to match multi lines.

Text Processing – Delete nth Line from a Matched String Using AWK or SED

sed seems like the right tool:

sed -i '/radius-server/!b;n;n;d' filename

How it works:

/radius-server/!b # as long as it's NOT 'radius-server' do nothing (branch to end)
n # read next line (replace current line with next line)
n # same as above - we now read 2 lines
d # delete the current line

UPDATE - to modify multiple files, simply use glob instead of filename, e.g.

sed -i '/radius-server/!b;n;n;d' *

Best Answer

Related Solutions

Grep string where next line does not contain string

Text Processing – Delete nth Line from a Matched String Using AWK or SED

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