Remove all lines between two strings

Question

In a sh shell script.

Given data in a text file:
string1
string2 gibberish
gibberish
string3 gibberish
string4

How could you use awk or sed to remove all lines between string2(inclusive) and string3(not including string 3)?

to end up with:
string1
string3
string4

Answer 1

Here's a sample regex substitution:

s/string2.*?(?=string3)//sg

Which will remove everything from string2 up to but not including string3.

Answer 2

Are string1, string2,string3, etc. each on different lines? In that case, you can use awk:

awk '/string2/{flag=1} /string3/{flag=0} !flag'

or sed:

sed '/string3/p; /string2/,/string3/d'

Answer 3

you can try this. Anything before "string2" will not be deleted.

awk 'BEGIN{f=0}
{
    match($0,"string2")
    if(RSTART){
        print substr($0,1,RSTART-1)
        f=1
        next
    }
    match($0,"string3")
    if(RSTART){
        $0=substr($0,RSTART)
        f=0
    }
}
f==0{print}
' file

output

$ cat file
string1 blah blah
text before string2 junk
gibberish
gibberis string3 text here
string4

$ ./shell.sh
string1 blah blah
text before
string3 text here
string4

Answer 4

The following will work in sed

sed  '
/string2/,/string3/bdeleting
b
:deleting
s/string3.*/string3/
/string3/b
d
'

presuming we are matching up to the first occurrence of string3 after string2