$ cat script.pl
use warnings;                                                                                                                                                                       
use strict;                                                                                                                                                                         
                                                                                                                                                                                    
@ARGV == 1 or die "Usage: perl $0 <input-file>\n";                                                                                                                                  
                                                                                                                                                                                    
my %field;                                                                                                                                                                          
my $printed_header = 0;                                                                                                                                                             
                                                                                                                                                                                    
while ( <> ) {                                                                                                                                                                      
        if ( /^\s*$/ ) {                                                                                                                                                            
        ## When found a blank line print data saved previously.                                                                                                                     
                                                                                                                                                                                    
                ## Print header once in the program.                                                                                                                                
                unless ( $printed_header ) {                                                                                                                                        
                        print_header();                                                                                                                                             
                        $printed_header = 1;                                                                                                                                        
                }                                                                                                                                                                   
                                                                                                                                                                                    
                print_data();                                                                                                                                                       
                                                                                                                                                                                    
        } else {                                                                                                                                                                    
        ## Data found, save it in a hash.                                                                                                                                           
                chomp;                                                                                                                                                              
                                                                                                                                                                                    
                ## $f -> field name.                                                                                                                                                
                ## $d -> data.                                                                                                                                                      
                my ($f,$d);                                                                                                                                                         
                                                                                                                                                                                    
                if ( /^field\d+:/ ) {                                                                                                                                               
                ## All fields but first one.                                                                                                                                        
                        ($f,$d) = split /:/;                                                                                                                                        
                } else {                                                                                                                                                            
                ## Field 1.                                                                                                                                                         
                        ($f,$d) = split;                                                                                                                                            
                        $d =~ s/:\s*$//;                                                                                                                                            
                }                                                                                                                                                                   
                $d =~ tr/"//d;                                                                                                                                                      
                $field{ $f } = $d;                                                                                                                                                  
        }                                                                                                                                                                           
}                                                                                                                                                                                   
                                                                                                                                                                                    
print_data();                                                                                                                                                                       
                                                                                                                                                                                    
sub print_data {                                                                                                                                                                    
        for my $key ( sort keys %field ) {                                                                                                                                          
                printf "%s ", $field{ $key };                                                                                                                                       
        }                                                                                                                                                                           
        print "\n";                                                                                                                                                                 

}

sub print_header {
        for my $key ( sort keys %field ) {
                printf "%s ", $key;
        }
        print "\n";
}
$ perl script.pl infile
field1 field2 field3 field4 
user1 data-cde data-pqr data-mno 
user1 data-dcb data-mxz data-zul 
user2 data-cqz data-xoq data-pos