Question

My understanding is that /[^\A] +/mg will match globally one or more spaces occurring other than at the beginning of the string or just after newline.

Apparently, I’m wrong.

#!/usr/bin/env perl
use strict;
use warnings;

my $str = "         word1     word2\n     word3     word4     word5\n";
print "str before = $str\n";
$str =~ s/[^\A] +/ /mg;
print "str after  = $str\n";

Output:

str before =          word1     word2
     word3     word4     word5

str after  =  word word2 word word word5

The desired output is:

str before =          word1     word2
     word3     word4     word5

str after  =          word1 word2
     word3 word4 word5

So the leading spaces are preserved in number but multiple spaces occurring after the beginning of each line are reduced to a single space.

I’m not finding what I’m looking for in perldoc perlretut nor perldoc perlre (even after searching through all the instances of “[^” with /\[\^). Many thanks, in advance.

Answer 1

In Perl, the most simple solution is: s/\S\K +/ /g;

See this demo.