/usr/bin/nmzgrep is in namazu2-index-tools 2.0.21-10.
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 | #! /usr/bin/perl -w
# -*- Perl -*-
#
# nmzgrep - search namazu-indexed documents for a given pattern and 
#           print lines matching the pattern.
# 
# $Id: nmzgrep.in,v 1.1.8.2 2004-09-19 03:37:44 opengl2772 Exp $
#
# Copyright (C) 1999 Satoru Takabayashi  All rights reserved.
#     This is free software with ABSOLUTELY NO WARRANTY.
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either versions 2, or (at your option)
#  any later version.
# 
#  This program is distributed in the hope that it will be useful
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
#  02111-1307, USA
#
use strict;
use FileHandle;
if (@ARGV == 0) {
    print "usage: nmzgrep [egrep's options] <pattern> [index]...\n";
    exit 1;
}
my @opts = ();
while (defined $ARGV[0] && $ARGV[0] =~ /^-/) {
    push @opts, $ARGV[0];
    shift @ARGV;
}
if (@ARGV == 0) {
    print "usage: nmzgrep [egrep's options] <pattern> [index]...\n";
    exit 1;
}
my $pattern = shift @ARGV;
my @indices = @ARGV;
my $command = "namazu -alR $pattern @indices |\
               xargs egrep @opts $pattern /dev/null";
my $fh = new FileHandle;
$fh->open("$command |");
if (defined $fh) {
    while (<$fh>) {
	print;
    }
} else {
    die "nmzgrep: $!";
}
exit 0;
 |