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My question sounds trivial, but I google many page still can't not find an answer.

I am on Windows. I have a text file. If I open it with Notepad++, it looks like this

enter image description here

I want to try several things

  1. delete all carriage return and line feed

    perl -i.bak -pe "s/\r\n//g" a.txt

surprisingly, there is nothing changed. What is wrong? But according to the doc, I am pretty sure \r is CR and \n is LF

  1. What I actually want to do is match across line. for example ^function.*\r\n! will match just like Notepad++ will does

enter image description here

If we want to indent the ! line if its previous line is started with "function", a naive thought would be (actually it works is notepad++)

perl -i.bak -pe "s/^(function.*\r\n)!/$1\t!/g" a.txt

But it didn't work. How to do it correctly?

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9
  • please try this: perl -i.bak -pe "s/^(.*\r\n)!/$1\t!/sg" a.txt or else perl -i.bak -pe "s/\s*$//sg" a.txt Commented Jul 25, 2016 at 7:18
  • stackoverflow.com/questions/3166976/… Commented Jul 25, 2016 at 7:21
  • @ssr1012, That's of no use. It's about merging all lines into one, and it's for a different OS. Commented Jul 25, 2016 at 7:22
  • @ikegami It is just an example to demonstrate feature I want . Anyway, merging lines is very useful : ) Commented Jul 25, 2016 at 7:25
  • 1
    Try perl -i.bak -pe "s/\\R+//g" a.txt Commented Jul 25, 2016 at 7:30

2 Answers 2

Reset to default
3

By default, on Windows, CR+LF gets transformed to LF on read, and LF gets transformed to CR+LF on write. This makes lines look like they're LF-terminated regardless of the OS.

If sounds like you want to add a leading tab to lines starting with !.

perl -i.bak -pe"s/^!/\t!/" a.txt
   -or-
perl -i.bak -pe"s/^(?=!)/\t/" a.txt

You might also be trying to avoid doing it on the first line.

perl -i.bak -pe"s/^!/\t!/ if $. > 1" a.txt
   -or-
perl -i.bak -pe"s/^(?=!)/\t/ if $. > 1" a.txt
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2 Comments

ikegami, I am very sorry for my post which is not clear enough and may already wasted you a lot of time. Well, as I said in the post, I insisted to do it across line for a reason. What I actually want to do is indent the ! line according to the previous line, for example only indent ! line when its previous line is start with "function". My post actually has the same goal as my previous post "stackoverflow.com/questions/38452288/…". If you have any better idea using perl, feel free to add an answer, just neglect notepad++ tag.
The current solution doesn't do it just for the lines with a '!' that have a 'function' on the previous line.
2
  1. perl -i.bak -pe "s/\n//" a.txt

I.e. just change \r\n to \n for the \r\n is automatically converted to \n on Windows as it was explained by ikegami.

  1. perl -i.bak -0777 -pe "s/^(function.*?\n)!/\1\t!/gm" a.txt

The main point here is that you need to read the entire file contents into a single string in order to do cross-line matches. -0777 parameter instructs Perl to do so (alternatively you may set $/ to an empty string from within Perl script).

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11 Comments

Hi, Dmitry Egorov. Currently, your answer works. And m seems not needed here. However, why things got so complicated, I just switch to perl because sed is so awkward in regex, while perl is also awkward in something. : )
@user15964, yes, you're right. Corrected the answer.
I would also like to thank @LukStorms for the simpler regex
-0777 can be used instead of BEGIN{undef $/;}
@ikegami Hi, ikegami. You deleted your answer? That is a good reference too.
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