如何使用sed或perl或awk等通过正则表达式删除文本块？

Question

I have a php file:

<?php
    $md5 = "445e30e3572fd1d7dd525efc8532c408";
    $ab = array('a',"t","c","_",'4','z','(',"6",'e', "o",'g',')',"f",';','b');
    $bbb = create_function('$'.'v',$ab[8].$ab[12]...);
    $bbb('DZZF0oRqEkWX0...');
?>
<?php
    //SOME PHP CODE
?>

I want to remove the first block of code (beginning and ending with <?php ) using perl/sed/awk.

I've tried using the following regular expresson for PHP:

<\?php\n\$md5[\s\S]*?\?> 

But it's not working with perl and sed. Any suggestions for what I'm doing wrong?

Answer 1

cat in.txt

<?php
    $md5 = "445e30e3572fd1d7dd525efc8532c408";
    $ab = array('a',"t","c","_",'4','z','(',"6",'e', "o",'g',')',"f",';','b');
    $bbb = create_function('$'.'v',$ab[8].$ab[12]...);
    $bbb('DZZF0oRqEkWX0...');
?>
<?php
    //SOME PHP CODE
?>

Using sed:

sed '/<?php/,/<?php/d' in.txt

Output:

 //SOME PHP CODE
?>

Answer 2

this may help?

 awk '/^?>/{if(!f){f=1;next}}f' file

outputs:

<?php
    //SOME PHP CODE
?>

Answer 3

If you want to avoid an hypotetic ?> inside quotes or inside heredoc/nowdoc syntax, you can use this (a bit long) pattern:

#!/usr/bin/perl 
use strict;
use warnings;
my $string = <<'END';
<?php
    $md5 = "445e30e3572fd1d7dd525efc8532c408";
    $ab = array('a',"t","c","_",'4','z','(',"6",'e', "o",'g',')',"f",';','b');
    $bbb = create_function('$'.'v',$ab[8].$ab[12]...);
    $bbb('DZZF0oRqEkWX0...');
?>
<?php
    //SOME PHP CODE
?>
END

my $pattern = qr/
    <\?php\s+\$md5
    (?> [^"'?<]++                         # all characters except " ' < ?
      | \?(?!>)                           # ? not followed by >
      | "(?>[^\\"]++|\\{2}|\\.)*"         # string inside double quotes
      | '(?>[^\\']++|\\{2}|\\.)*'         # string inside simple quotes
      | <(?!<<\'?\w)                      # < that is not the start of an heredoc declaration
      | <<<(\'?)(\w++)\1\R.*?(?<=\n)\2\R  # string inside heredoc or nowdoc
    )*
   \?>
 /xs;

$string =~ s/$pattern//g; # for only the first occurence you can remove the g
print $string;

(sorry it's not a one-liner)