MultiLine Replace (multiple hosts in hostsfile)

rugabunda · Sep 16, 2018, 2:20 AM

I have a hosts file that is over run with too many entries most of which I don’t want and some which I do. I have another hosts files containing only those hosts I don’t want. How can I take the list of hosts I don’t want, and multi-line remove/replace them with nothing in my original hosts file?

I have tried toolbucket multifind and replace, but it searches the multi line as one contiguous line, and not each independent line as an independent entry. there should be an option for this. how simple and how important such a feature could be. anyone know how to do this?

rugabunda · Sep 16, 2018, 2:54 AM

I have tried tool bucket multi-line replace, text crawler, search and replace tool, and it does not work. these multi line search tools combines the exact string of multiple lines together, rather than searching for each line independently. I have 17 thousand unique lines I want to remove from the text, and maybe 150 I want to keep. A SIMPLE option selection box to treat each new line in the find dialogue as an individual search/replace expression would fit the bill and save users massive headaches the world around.

rugabunda · Sep 16, 2018, 3:33 AM

see I can search for one line, and replace that no problem. but i can’t just as easily insert a multi-line of the entire hosts lists and replace it. should be simple imo.

guy038 · Sep 17, 2018, 9:33 AM

Hi, @rugabunda and All,

This problem has been already discussed many times ! So :

You have a first file, named File_A.txt, which contains a list of… whatever you like !
You have a second file, named File_B.txt, which contains the same kind of list, with fewer lines than in File_A.txt

And you would like to delete, in File_A.txt, all the lines, which are, ALSO, present in File_B.txt

Wouldn’t you ?

Not difficult with regular expressions ;-)). Note that the following regex S/R compares complete lines, only !

Here is the method :

Start Notepad++
Copy/paste all contents of the main File_A.txt file in a new tab
At the end of this main list, add a new line of, at least 3 dashes ( --- )
now, append all contents of the File_B.txt file, AFTER this line
Open the Replace dialog ( Ctrl + H )
Select the Regular expression search mode
Tick the Wrap around option

SEARCH (?-s)^(.+\R)(?=((?s).+?\R)?\1)|(?s)^---.+

REPLACE Leave EMPTY

Click, once on the Replace button or several times on the Replace button

Et voilà ! In the new N++ tab, any line, which was, both, present in the two files, has been deleted, as well as any possible duplicate lines, in the main File_A.txt file !

For instance, let’s consider a File_A.txt contents, below :

Smith Oliver
Jones Olivia
TaylorGeorge
Brown Amelia
Williams Harry
Wilson Emily
Johnson Jack
Davies Isla
Davies Isla
Davies Isla
Robinson Jacob
Wright Ava
Green Lily
Thompson Noah
Evans Jessica
Walker Charlie
White Isabella
Roberts Muhammad
Green Lily
Hall Thomas
Wood Ella
Jackson Oscar
Clarke Mia

Note that the complete names Davies Isla and Green Lily has, respectively, 2 and 1 duplicates, in that example list !

Then, let’s suppose the following File_B.txt contents :

Jackson Oscar
Green Lily
Thompson Noah
Jackson Oscar
Williams Harry

Again, note the the complete name Jackson Oscar has 1 duplicate

Once you added the separation line and gathered the contents of the two files, with File_A.txt in first position, you’ll get, in the new tab, the text :

Smith Oliver
Jones Olivia
TaylorGeorge
Brown Amelia
Williams Harry
Wilson Emily
Johnson Jack
Davies Isla
Davies Isla
Davies Isla
Robinson Jacob
Wright Ava
Green Lily
Thompson Noah
Evans Jessica
Walker Charlie
White Isabella
Roberts Muhammad
Green Lily
Hall Thomas
Wood Ella
Jackson Oscar
Clarke Mia
---
Jackson Oscar
Green Lily
Thompson Noah
Jackson Oscar
Williams Harry

After performing the regex S/R :

SEARCH (?-s)^(.+\R)(?=((?s).+?\R)?\1)|(?s)^---.+

REPLACE Leave EMPTY

You’ll obtain the expected list :

Smith Oliver
Jones Olivia
TaylorGeorge
Brown Amelia
Wilson Emily
Johnson Jack
Davies Isla
Robinson Jacob
Wright Ava
Evans Jessica
Walker Charlie
White Isabella
Roberts Muhammad
Hall Thomas
Wood Ella
Clarke Mia

Notes :

As usual, at beginning, the (?-s) modifier means that the dot . character will match any single standard character
Then, the part ^(.+\R), matches, from beginning of line, ^ , all the characters, of any non-blank line, .+ , with its line-break characters \R , stored as group 1, due to the parentheses (....)
But ONLY IF the regex ((?s).+?\R)?\1, contained in a positive look-ahead structure (?=.......) is verified
That is to say, if a second occurrence of the group 1 ( the complete line ), \1 is found, after an optional block, (....)? , of complete lines, (?s).*?\R, which represents the shortest non-null range of any character, .+? ( standard or EOL ones ) due to the (?s) modifier and ending with a line-break, \R
Now, when no more duplicates can be found, the regex engine tries the second alternative of the search regex, after the | alternation symbol, that is to say the regex (?s)^---.+, which grabs the longest range of any character, from the separation line till the very end of the file, due to the (?s) modifier which means that dot . matches any single character ( standard and EOL one )
In replacement, all the lines or block matched are, simply, deleted, as the replacement zone is empty

Best Regards,

guy038

Scott Sumner · Sep 16, 2018, 12:56 PM

@rugabunda

I’m concerned about you throwing about the terminology “multi line” without really explaining what that means to your task at hand. Sure, it is 100% clear to you, but to people that might try to help you…it may lead to a misunderstanding. Sure if @guy038 has giving you enough info to move forward, go for it, but if not, how about showing some sample before and desired/after data to elicit further help?

rugabunda · Sep 17, 2018, 1:11 PM

Thank you @guy038, IT WORKED! you figured it out like a pro right off the bat. Your expressions worked. Thank you for your detailed and able assistance!

As for what I stated about simplified multi line searching, please read it again with his correct interpretation in context. I would like to perform the same operation without having to use a single expression, it should be as easy as copy/paste click replace, done. Were there a box one can check that states “treat each line as independent search” or “line-by-line search” something to that effect. So that each contiguous line in the search dialogue box performed the search and replace independently, one after another. As it stands I can search for one line, and replace that no problem. but i can’t just as easily insert a multi-line of the entire hosts lists and hit replace all, with a tick box that treats each individual line as an independent search. should be simple imo.

Thank you once again! You are awesome guy038!

Scott Sumner · Sep 17, 2018, 1:11 PM

@rugabunda

I still think the terminology used is bad. I’d refer to this generically as a “list-based” replacement or a “lookup-table” replacement. “Multiline” means something totally different, at least to me…

dinkumoil · Sep 17, 2018, 1:43 PM

@rugabunda

A generic workaround would be the following Windows console command:

(for /f "usebackq delims=" %a in ("File_A.txt") do @(findstr /x /c:"%a" "File_B.txt" 1>NUL 2>NUL || echo %a)) > "File_C.txt"

This would produce a file File_C.txt containing all lines of File_A.txt which are not part of File_B.txt.

Please note:

The command above is designed for direct execution from a console window. If you want to put it in a batch file you have to double the %-sign before the variable %a.
If you want to search case-insensitive add the switch /i to the findstrcommand.

guy038 · Sep 17, 2018, 7:44 PM

Hi, @rugabunda, @scott-sumner, @dinkumoil and All,

@dinkumoil :

Very clever use of the two DOS commands for and findstr !

It’s still possible to shorten a bit this command line, as :

The filesnames, without extension, has less than 8 characters
The filenames do not contain any space character

=> Then, the option usebackq, of command for, is not necessary and double-quotes, surrounding filenames, are useless, too !

Secondly, if we suppose that File_C.txt does not exist in current directory, we can omit the outer commands grouping (.....) and use the DOS append to file symbol >>
Thirdly, it better to suppress the error redirection to the NUL file 2>NUL because, if File_B.txt does not exist in current folder, you’ll see the error message on the console, as well as File_A.txt

So, if that command line is not part of batch file, the final syntax could be :

for /f "delims=" %L in (File_A.txt) do @(findstr /x /c:"%L" File_B.txt 1>NUL || echo %L) >> File_C.txt

Note that I changed the %a variable, storing each line of File_A.txt, with the %L syntax (for L ine )

@rugabunda :

I forgot to speak about case sensitivity ! So, the regex search should be :

SEARCH (?i-s)^(.+\R)(?=((?s).+?\R)?\1)|(?s)^---.+ , if you need a case-insensitive search
SEARCH (?-is)^(.+\R)(?=((?s).+?\R)?\1)|(?s)^---.+ , if you need a case-sensitive search

Regards,

guy038

P.S. :

@dinkumoil :

Your “DOS” method does not delete any duplicate of File_A.txt, which is not in File_B.txt, of course. Anyway, it’s just a “side-effect” of my regex ;-))

dinkumoil · Sep 17, 2018, 9:29 PM

@guy038

Batchscript is a mine field and thus over the years I got used to some best practices to avoid certain problems.

One of these problems are blanks in file names, so I always surround file names with double quotes. Maybe the script gets changed in the future by an unexperienced user and he uses file names with blanks, with my double-quote-policy no problem.

The command grouping with (...) around the FOR loop is intentionally. It gives the loop a big performance boost in case the script is used to write a lot of lines because the output file has to be opened only for one time. @rugabunda talks of 17000 lines he wants to process, so it’s a pretty good idea to keep an eye on performance. Furthermore your solution with appending the script’s output to the resulting file leads to the necessity to clear the output file before every script run.

dinkumoil · Sep 17, 2018, 9:42 PM

@guy038

Addendum: Because of my last point in the posting above it is also neccessary to redirect error messages of FINDSTR to the NUL device to avoid that they are written to the output file. I also think that they are useless in the context of the problem discussed here.

In summary, my command has not much potential to be optimised. ;)

guy038 · Sep 17, 2018, 10:31 PM

Hi, @rugabunda, @scott-sumner, @dinkumoil and All,

Ah, many thanks, Dinkumoil, for your optimization advices !

Of course, having 17,000 messages “impossible to open File-B.txt” is rather idiot ! I did not realize this, as working on my tiny File_A.txt :-(

Thus, appending 17,000 times, a line to File_C.txt is not very efficient, too, as you said !

Finally :

If you previously chose some basic filenames, without spaces, this syntax should be enough :

(for /f "delims=" %L in (File_A.txt) do @(findstr /x /c:"%L" File_B.txt 1>NUL 2>NUL || echo %L)) > File_C.txt

If your filenames may be long, with some space characters, the @dinkumoil solution, with the usebackq option and filenames surrounded by double quotes, is safer !

Cheers,

guy038