comment on

G'day Special_K,

I use Cygwin. I'm using the latest version, 3.3.6. I do a full update of "pending" components every week; my last update was about an hour ago. So, everything related to Cygwin below is up-to-date.

I also run Perlbrew. I recommend you do the same. I completely ignore whatever Perl components Cygwin has installed. I can easily switch between whatever Perl versions I want to use:

$ which perl
/home/ken/perl5/perlbrew/perls/perl-5.36.0/bin/perl

$ perlbrew list
 * perl-5.36.0
   perl-5.34.0
   perl-5.33.5
   perl-5.32.0
   perl-5.30.0

$ perlbrew switch perl-5.30.0

$ which perl
/home/ken/perl5/perlbrew/perls/perl-5.30.0/bin/perl

$ perlbrew switch perl-5.36.0

$ which perl
/home/ken/perl5/perlbrew/perls/perl-5.36.0/bin/perl
[download]

If you're up-to-date, I'm surprised you've even got /usr/bin/perl5.30.3. Here's what I got from Cygwin:

$ ls -al /usr/bin/perl
-rwxr-xr-x 2 ken None 12800 Aug 14  2021 /usr/bin/perl

$ ls -al /usr/bin/perl*
-rwxr-xr-x 2 ken None 12800 Aug 14  2021 /usr/bin/perl.exe
-rwxr-xr-x 2 ken None 12800 Aug 14  2021 /usr/bin/perl5.32.1.exe
-rwxr-xr-x 2 ken None 45259 Aug 14  2021 /usr/bin/perlbug
-rwxr-xr-x 1 ken None   262 Aug 14  2021 /usr/bin/perldoc
-rwxr-xr-x 1 ken None 57920 Feb  7  2021 /usr/bin/perli11ndoc
-rwxr-xr-x 1 ken None 10813 Aug 14  2021 /usr/bin/perlivp
-rwxr-xr-x 1 ken None 12047 Oct  4 17:26 /usr/bin/perlsh
lrwxrwxrwx 1 ken None    48 Aug 13 10:59 /usr/bin/perltex -> /usr/shar
+e/texmf-dist/scripts/perltex/perltex.pl
-rwxr-xr-x 2 ken None 45259 Aug 14  2021 /usr/bin/perlthanks

$ /usr/bin/perl -v

This is perl 5, version 32, subversion 1 (v5.32.1) built for x86_64-cy
+gwin-threads-multi
(with 7 registered patches, see perl -V for more detail)
...
[download]

I attempted to replicate what you're showing us, but couldn't. However, although you've shown the code and the output, you don't say how you ran it: ./script.pl; perl script.pl; /usr/bin/perl script.pl; /usr/bin/perl5.30.3 script.pl; etc.

Try running variations of the following to see what's in @INC and where your modules are located (from %INC info):

$ /usr/bin/perl5.32.1 -E 'use strict; use warnings; say for @INC; use 
+Data::Dumper; print Dumper \%INC;'
/usr/local/lib/perl5/site_perl/5.32/x86_64-cygwin-threads
/usr/local/share/perl5/site_perl/5.32
/usr/lib/perl5/vendor_perl/5.32/x86_64-cygwin-threads
/usr/share/perl5/vendor_perl/5.32
/usr/lib/perl5/5.32/x86_64-cygwin-threads
/usr/share/perl5/5.32
$VAR1 = {
          'feature.pm' => '/usr/share/perl5/5.32/feature.pm',
          'XSLoader.pm' => '/usr/share/perl5/5.32/XSLoader.pm',
          'bytes.pm' => '/usr/share/perl5/5.32/bytes.pm',
          'Exporter.pm' => '/usr/share/perl5/5.32/Exporter.pm',
          'constant.pm' => '/usr/share/perl5/5.32/constant.pm',
          'Data/Dumper.pm' => '/usr/lib/perl5/5.32/x86_64-cygwin-threa
+ds/Data/Dumper.pm',
          'warnings.pm' => '/usr/share/perl5/5.32/warnings.pm',
          'overloading.pm' => '/usr/share/perl5/5.32/overloading.pm',
          'Carp.pm' => '/usr/share/perl5/5.32/Carp.pm',
          'strict.pm' => '/usr/share/perl5/5.32/strict.pm',
          'warnings/register.pm' => '/usr/share/perl5/5.32/warnings/re
+gister.pm'
        };
[download]

"If I install a new version of perl, do I need to install new copies of every module that was installed for the prior version of perl I was using? "

In general, you'll need to install all non-core modules (i.e. modules from CPAN, that you wrote yourself, that came from your $work, and so on). However, as you seem to have both a v5.30 and a v5.32, I'm not sure what you've done and what you need to do.

I keep a list of all of my non-core modules and install them (using the cpan utility) every time I install a new Perl version via Perlbrew. I'm reasonably certain that there are short-cuts for doing this, but I like to keep a close eye on all module installations (and any problems they might have). Other monks may provide you with different ways to do this.

"If I install a new version of perl but I want some scripts to use the prior version of perl, do I need to manually edit each of those scripts to point to the old version, as I have done in my second sample code block above?"

I use this shebang for all of my scripts:

#!/usr/bin/env perl
[download]

I just switch to whatever Perl version I want (using Perlbrew) and run the script as is. Sometimes I want to test a script against several versions of Perl: this is an easy way to achieve that.

Without Perlbrew, you can just use something like this:

$ /usr/bin/perl5.30.3 script.pl
$ /usr/bin/perl5.32.1 script.pl
[download]

Continually making changes to the shebang is a pain and error-prone. I wouldn't recommend it.

Also note the distinct absence of -w in any of my code in this response. I strongly recommend you use the warnings pragma instead. See "perlrun: -w" for more about that (note the "... normally, the lexically scoped use warnings pragma is preferred.").

— Ken

In reply to Re: help fixing module paths after upgrading perl in cygwin by kcott
in thread help fixing module paths after upgrading perl in cygwin by Special_K

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