regex - 在perl中对文本 block 进行排序

Question

我有一个看起来像这样的文件:

SECTION1 id name  
 sub section1
 sub section2
SECTION2 id name  
 sub section3
 sub section4
 sub section6
SECTION1 id name  
 sub section7
 sub section8
SECTION3 id name  
 sub section9
 sub section10
 sub section11
 sub section12
SECTION2 id name  
 sub section13
 sub section14
SECTION1 id name  
 sub section15
 sub section16
SECTION3 id name  
 sub section17
 sub section18

我需要按部分对这个文件进行排序。我唯一知道的是我有“SECTION1”、“SECTION2”和“SECTION3”。排序后的预期输出是:

SECTION1 id name  
 sub section1
 sub section2
SECTION1 id name  
 sub section7
 sub section8
SECTION1 id name  
 sub section15
 sub section16
SECTION2 id name  
 sub section3
 sub section4
 sub section6
SECTION2 id name  
 sub section13
 sub section14
SECTION3 id name  
 sub section9
 sub section10
 sub section11
 sub section12
SECTION3 id name  
 sub section17
 sub section18

在 perl 中或使用 grep、sed 等实用程序是否有任何简单的方法可以做到这一点？

Answer 1

另一种使用 perl 的方法:

假设 infile 包含问题的内容和以下 script.pl 的内容:

use warnings;
use strict;
use sort qw/stable/;

my ($section, @section);

while ( <> ) { 

    ## Save text if first line or when line doesn't begin with 'SECTION' word.
    if ( $. == 1 || $_ !~ m/\ASECTION\d+/ ) { 
        $section .= $_; 
        next unless eof;
    }   

    ## Save the text and the number of section.
    if ( $section =~ m/\ASECTION(\d+)/ ) { 
        push @section, [ $1, $section ];
        $section = q||;
    }   

    ## Begin to save next section.
    $section .= $_; 
}

## Print them sorted by section number.
for ( sort { $a->[0] <=> $b->[0] } @section ) { 
    printf qq|%s|, $_->[1];
}

像这样运行它:

perl script.pl infile

输出如下:

SECTION1 id name  
 sub section1
 sub section2
SECTION1 id name  
 sub section7
 sub section8
SECTION1 id name  
 sub section15
 sub section16
SECTION2 id name  
 sub section3
 sub section4
 sub section6
SECTION2 id name  
 sub section13
 sub section14
SECTION3 id name  
 sub section9
 sub section10
 sub section11
 sub section12
SECTION3 id name  
 sub section17
 sub section18