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Valeriu
Asked: 2017-01-22 13:53:25 +0800 CST

Grep by block of text\lines

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I have the text, that contains some lines. So, i need to make GREP of several lines. For example, i have repeating text and i should GREP get lines, that have this repeating key-words.

grep -o "test|test2" textfile

My text:

123|never for your|test
123421|never for your|test2
123412|never for your|test3
12341|never for your|test4
12311|never for your|test2
123312312|never for your|test
123321312|never for your|test2

I should have:

123|never for your|test
123421|never for your|test2
123312312|never for your|test
123321312|never for your|test2

It works, but it doesn't work how i want. It searchs in text, all words "test" & "test2". But i want to get textblocks, like some pattern, where only after "test" comes "test2". Have you got any ideas ?

scripting bash shell shell-scripting

4 Answers

  1. Best Answer

    Brief shell script using sed. Makes a list of line numbers for the second case, and compares against line numbers for the first case. Prints matching pairs. Uses the first argument as the file name. Could easily be extended to take second and third arguments as patterns to match. Could save as findnext.sh, and run:

    $ sh findnext.sh testfile

    Should be quick as it only involves two passes over the file, and has the advantage of being completely portable.

    #!/bin/sh 
# Line numbers matching test1
mt2=$(sed -ne '/test1/=' < $1 | tr '\n' '/')

for l in $(sed -ne '/test/=' < $1); do
    nextline=$(expr $l + 1)
    [ "${mt2#*$nextline/}" != "$mt2" ] && sed -ne $l,${nextline}p <$1
done
    • 2

  2. You can try grep -E or egrep. Please try it like this

    #this will show lines that have test or test2
    grep -E "test|test2" file

    If you want to show line that has test and test2 like this test|test2 do this

    # This will show lines that has test|test2
    grep "test\|test2" file
    • 1

  3. awk may be your tool for this:

    awk '/test$/, /test2$/' < block-text-lines.txt

    the general form is:

    awk '/start-pattern/, /end-pattern/{command}'

    But since the command block defaults to print, just the start and end patterns do the trick.

    Check out man awk or the Gnu Awk User's Guide for way more detail.

    • 0 
  4. grep -A 1 "test$" in.txt | grep -B 1 "test2$"

    In grep manual

    -A NUM Print NUM lines of trailing context after matching lines.

    -B NUM Print NUM lines of leading context before matching lines.

    The command grep -Pzo ".*test$\n.*test2$" in.txt also works, but in the manual is "This is highly experimental and grep -P may warn of unimplemented features."

    • 0