Grep string where next line does not contain string

command linegrepsearchtext processing

I want to search all files inside a directory and its subdirectories for lines containing a certain string, but I want to exclude those results that contain a different certain string in the line immediately after it.

For example, this:

foo1 searchString bar
foo1 excludeString bar

foo2 searchString bar
something else

foo3 searchString bar

foo3 excludeString bar

foo4 searchString bar

should return this:

foo2 searchString bar
foo3 searchString bar
foo4 searchString bar

I know that -A prints multiple lines, and that -v excludes results. But my current approach of grep -r -A 1 "searchString" | grep -v "excludeString" obviously can't work.

Is there a way to tell the second grep that it should also remove the previous line if it finds a match? Or some other way how I might achieve this?

Performance isn't my primary concern; It would be nice if the command is relatively easy to remember though.

Best Answer

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.

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How to print all the lines not containing a string along with adjacent lines

I'm not sure how structured your data is but if it is just as you show, how about the following:

grep -B2 'Auto-Installed: [^1]'

That assumes that every stanza includes an Auto-Installed line, which might not be correct.

Here's an awk program which I think does exactly as you asked.

awk 'BEGIN{deleted=3}
     !deleted{printf "%s",l[NR%3]}
     deleted {--deleted}
     {l[NR%3]=/./?$0"\n":$0}
     /Auto-Installed: 1/{deleted=3}
     END{for(i=NR+deleted;i<NR+3;++i)printf "%s",l[i%3]}'

Printing filename along with grep results in find -exec

To get each filename printed to the output and THEN have the grep results corresponding to that file printed after, you could wrap the -exec foo {} | grep pipe in a shell:

find . -name '*.o' -type f -print -exec sh -c 'foo "$1" | grep "bar"' sh {} \;

To to make the -H argument of grep work with standard input, if your version of grep supports the --label= option you could do

find . -name '*.o' -type f -exec sh -c '
  foo "$1" | grep -H --label="$1" "bar"
' sh {} \;

or (if your find supports the + multi-argument alternative to \;):

find . -name '*.o' -type f -exec sh -c '
  for f; do foo "$f" | grep -H --label="$f" "bar"; done
' sh {} +

Best Answer

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How to print all the lines not containing a string along with adjacent lines

Printing filename along with grep results in find -exec

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