Try:
s/[^\n]+\{TT\}\nD.+?(\{TT\}|$)/$1/gs

[download]
Explained:
  • s/ startes a replace, because we want to replace the {TT}/d - blocks by "nothing" (which means just deleting them)
  • ^\n+ selectes all text (everything which is no newline char = \n) as you said "...delete all chars from the line which has text {TT}", remove this part if you want the chars before the {TT} to stay.
  • \{TT\}\nD matches your "if there is a char D below the {TT}" = A {TT} followed by a newline followed by a D
  • .+? matches everything from the newline following the D, but the ? says that we wan't to match as few as possible chars (missing it would match everything beginning from here)
  • (\{TT\}|$) finally selects the next {TT} and stops the match before at this point. The |$ means that we also accept a "End of string" as match. The last {TT}\nD - block wouldn't be deleted otherwise. You could also add ^\n+ after the ( to keep the whole line which holds the next {TT}
  • /$1 holds the replacement string for the earlier match, in this case the first ( ) block - which is our "beginning of next block" marker
  • /gs has two options: g for "replace all" and s for "make . also match \n" which is important for the .+? - block - it won't work over newlines otherwise.
    • This solution will do what you want as long as you could get the data into a variable. My personal choice would be this short way as long as the amount of data is below 25% of the memory your script may eat. Assuming you could give 1 GB of RAM to it would allow 250GB of data being processed, maybe more.

    In reply to Re: delete lines till by Sewi
    in thread delete lines till by Anonymous Monk

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