/usr/bin/marc2xml is in libmarc-xml-perl 1.0.2-1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 | #!/usr/bin/perl
eval 'exec /usr/bin/perl  -S $0 ${1+"$@"}'
    if 0; # not running under some shell
=head1 NAME
marc2xml - convert a MARC file to XML
=head1 SYNOPSIS
    # convert a file 
    % marc2xml marc.dat > marc.xml
    # or use in a pipeline
    % cat marc.dat | marc2xml > marc.xml
=head1 DESCRIPTION
marc2xml is a command line utility for converting MARC21 bibliographic
data to XML using the Library of Congress Slim Schema. Conversion is 
handled using the MARC::Record and MARC::File::XML packages.
=cut
use strict;
use warnings;
use MARC::Record;
use MARC::Batch;
use MARC::File::XML;
use IO::File;
my $file = shift;
my $fh; 
## read from a file?
if ( $file ) { 
    fatal( "no such file: $file" ) if ! -r $file;
    $fh = IO::File->new( $file );
} 
## or from STDIN?
else {
    $fh = \*STDIN;
}
## set up intput/output for utf8 encoding
binmode( STDOUT, ':utf8' );
binmode( $fh, ':bytes' );
my $found = 0;
my $batch = MARC::Batch->new( 'USMARC', $fh );
# be lenient, it's MARC afterall :)
$batch->warnings_off();
$batch->strict_off();
while ( my $record = $batch->next() ) { 
    if ( ! $found ) { 
        print MARC::File::XML::header();
        $found = 1;
    }
    print MARC::File::XML::record( $record );
}
print MARC::File::XML::footer() if $found;
sub fatal {
    print STDERR shift, "\n";
    exit( 1 );
}
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