Remove lines corresponding to first 7 matches of a string (in a pattern range)

Question

I need to remove the lines corresponding to first 7 occurrences of a string from a txt file in a pattern range (string1-string2).

Example of txt file content:

whatever
xpto string1 foo2
whatever1 
string2
xpto1 another_foo
xpto string2

string2 foo1

whatever
string2 another_xpto
string2 string2
foo xpto string2 whatever 
anything else foo string2
xpto
string2
foo whatever

I need a solution with sed ranges, something like that:

sed '/string1/,/string2/d' file.txt

The point is that I don't know how to extend /string2/ until the line corresponding to seventh match of string2. The desirable output should be:

whatever
anything else foo string2
xpto
string2
foo whatever

Answer 1

sed -e:t -e'/string1/!b' -e'/\(.*string2\)\{7\}/d;N;bt'

Answer 2

awk '/string1/{c=7}; c<1; {c-=gsub(/string2/, "&")}' file

c is initially 0, and set to 7 if string1 is found. The line is printed whenever c<1.

The gsub function returns the number of times string2 appears on each line. The counter c is decremented by that value.

Answer 3

Here's one way to do what you want using literal strings:

$ cat tst.awk
BEGIN { lgth = length(end) }
index($0,beg) { inBlock = 1 }
inBlock {
    rec = $0
    while ( pos = index(rec,end) ) {
        if ( ++cnt >= min ) {
            inBlock = 0
        }
        rec = substr(rec,pos+lgth)
    }
    next
}
{ print }

$ awk -v beg='string1' -v end='string2' -v min=7 -f tst.awk file
whatever
anything else foo string2
xpto
string2
foo whatever

The above will interpret backslashes in the strings (e.g. \t would become a tab), if that's an issue let me know as it's an easy workaround, e.g. using ENVIRON[].

Answer 4

Perl

perl -ne '
  if (my $e = /string1/ ... s/string2/$&/g >= 7) {
      $_ .= $e =~ /E0/ ? next : <>, redo;
  }
  print;
' file

---

Posix sed:

sed -ne '
  /string1/!{p;d;}
  :loop
    n
    /string2/H
    g;s//&/7;t
  b loop
' file

---

Output:

whatever
anything else foo string2
xpto
string2
foo whatever