Ubuntu – Installing TeXLive from ISO

I have downloaded texlive2017-20170524.iso from http://muug.ca/mirror/ctan/systems/texlive/Images/.

and tried to mount it with both "Open with archive mounter" (by right-clicking on it) and also "Open with –> Disk image mounter"

They are both successful in mounting.

When I cd to the mounted location and run ./install-tl (also tried ./install-tl), it gives me this error:

TeXLive/TLUtils.pm did not return a true value at ./install-tl line 54.
BEGIN failed--compilation aborted at ./install-tl line 54.

Here are the first 60 lines of install-tl

#!/usr/bin/env perl
# $Id: install-tl 44407 2017-05-18 21:25:39Z karl $
# 
# Copyright 2007-2017
# Reinhard Kotucha, Norbert Preining, Karl Berry, Siep Kroonenberg.
# This file is licensed under the GNU General Public License version 2
# or any later version.
#
# Be careful when changing wording: *every* normal informational message
# output here must be recognized by the long grep in tl-update-tlnet.
#
# TODO:
# - with -gui pop up a transient window showing:
#      testing for compressed archive packages ...
#      testing for uncompressed live system ...
#      testing for network access ...
#      loading tlpdb, this can take some time ...
#   (that, and maybe some others can be done with the waitVariableX
#   thingy as described in the Perl/Tk book in the chapter that can be
#   found on the net)   (Werner 28.10.08)

my $svnrev = '$Revision: 44407 $';
$svnrev =~ m/: ([0-9]+) /;
$::installerrevision = ($1 ? $1 : 'unknown');

# taken from 00texlive.config: release, $tlpdb->config_release;
our $texlive_release;

BEGIN {
  $^W = 1;
  my $Master;
  my $me = $0;
  $me =~ s!\\!/!g if $^O =~ /^MSWin/i;
  if ($me =~ m!/!) {
    ($Master = $me) =~ s!(.*)/[^/]*$!$1!;
  } else {
    $Master = ".";
  }
  $::installerdir = $Master;

  # All platforms: add the installer modules
  unshift (@INC, "$::installerdir/tlpkg");
}

use Cwd 'abs_path';
use Getopt::Long qw(:config no_autoabbrev);
use Pod::Usage;
use POSIX ();

use TeXLive::TLUtils qw(platform platform_desc sort_archs
   which getenv win32 unix info log debug tlwarn ddebug tldie
   member process_logging_options rmtree wsystem
   mkdirhier make_var_skeleton make_local_skeleton install_package copy
   install_packages dirname setup_programs native_slashify forward_slashify);
use TeXLive::TLPOBJ;
use TeXLive::TLPDB;
use TeXLive::TLConfig;
use TeXLive::TLCrypto;
use TeXLive::TLDownload;
use TeXLive::TLPaper;

I have also tried copying the contents to my hard-drive (so it is no longer in ISO format), as I have had problems before running applications directly from an ISO. It still gives me the above error.

Question: How can I install TeXLive to my system using texlive2017-20170524.iso?
(I'd much rather use an offline installer rather than sudo apt-get install texlive)

Here is what I see on the terminal:

Me@Computer:~/Desktop$ cd ~/Desktop
Me@Computer:~/Desktop$ mkdir mountpoint
Me@Computer:~/Desktop$ sudo mount -o loop texlive2017-20170524.iso mountpoint
[sudo] password for Me: 
mount: /dev/loop0 is write-protected, mounting read-only
Me@Computer:~/Desktop$ cd mountpoint/
Me@Computer:~/Desktop/mountpoint$ ./install-tl
TeXLive/TLUtils.pm did not return a true value at ./install-tl line 54.
BEGIN failed--compilation aborted at ./install-tl line 54.
Me@Computer:~/Desktop/mountpoint$