PERL5LIB different than 'use lib'

saintmike has asked for the wisdom of the Perl Monks concerning the following question:

If I want to install a CPAN module in a location that doesn't interfere with my package manager, I typically use

    perl Makefile.PL INSTALLBASE=/home/me/perl-lib
[download]

and then use

    PERL5LIB=/home/me/perl-lib/lib/perl5 perl-script
[download]

to run scripts using that new hierarchy of perl libs.

However, instead of using an ENV variable, I'd like to use code like

    use lib '/home/me/perl-lib/lib/perl5';
[download]

which, unfortunately, and contrary to the explanation in perlrun, isn't the same. For example, if you have architecture-dependent code that ends up in something like /home/me/perl-lib/lib/perl5/i686-linux-thread-multi, then PERL5LIB set to /home/me/perl-lib/lib/perl5 will find it, while 'use lib' won't.

Questions:

What are you doing to keep Perl modules installed by your package manager and CPAN modules separate?
Is INSTALLBASE still the recommended way of installing modules in a different than the standard location with MakeMaker?
Is there a directive in Perl that does what PERL5LIB does (without using PERL5LIB)?

Thanks for any insight.

Comment on PERL5LIB different than 'use lib' Select or Download Code

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Re: PERL5LIB different than 'use lib' by toolic (Bishop) on May 07, 2009 at 02:34 UTC
This is a quote from lib: For each directory in LIST (called $dir here) the lib module also checks to see if a directory called $dir/$archname/auto exists. If so the $dir/$archname directory is assumed to be a corresponding architecture specific directory and is added to @INC in front of $dir. If there is a subdirectory named "auto", then use lib seems to behave more like `PERL5LIB` in that it will also search in the architecture-dependent subdirectory for your module.	[reply] [d/l]
Re^2: PERL5LIB different than 'use lib' by almut (Canon) on May 07, 2009 at 03:01 UTC
also checks to see if a directory called $dir/$archname/auto exists... Both `PERL5LIB` and `use lib` should behave the same in this respect. For example $ mkdir -p testlib/x86_64-linux-gnu-thread-multi/auto $ PERL5LIB=testlib perl -e'print join"\n",@INC' testlib/x86_64-linux-gnu-thread-multi testlib /etc/perl /usr/local/lib/perl/5.8.8 /usr/local/share/perl/5.8.8 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.8 /usr/share/perl/5.8 /usr/local/lib/site_perl $ perl -Mlib=testlib -e'print join"\n",@INC' testlib/x86_64-linux-gnu-thread-multi testlib /etc/perl /usr/local/lib/perl/5.8.8 /usr/local/share/perl/5.8.8 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.8 /usr/share/perl/5.8 /usr/local/lib/site_perl [download] (the same applies to `-Itestlib`, btw)	[reply] [d/l] [select]
Re^3: PERL5LIB different than 'use lib' by tilly (Archbishop) on May 07, 2009 at 23:30 UTC
You'd think they should, but they don't. Try the following: $ PERL5LIB=/no/such/dir perl -le 'print for @INC' > foo $ PERL5LIB= perl -le 'use lib "/no/such/dir"; print for @INC' > bar $ diff -u foo bar--- foo 2009-05-07 16:24:12.000000000 -0700 +++ bar 2009-05-07 16:24:32.000000000 -0700 @@ -1,12 +1,3 @@ -/no/such/dir/5.8.6/x86_64-linux-thread-multi -/no/such/dir/5.8.6 -/no/such/dir/x86_64-linux-thread-multi -/no/such/dir/5.8.5 -/no/such/dir/5.8.4 -/no/such/dir/5.8.3 -/no/such/dir/5.8.2 -/no/such/dir/5.8.1 -/no/such/dir/5.8.0 /no/such/dir /usr/lib64/perl5/5.8.6/x86_64-linux-thread-multi /usr/lib/perl5/5.8.6 [download] And now we see the difference that saintmike was talking about. If you put stuff in $ENV{PERL5LIB}, it adds a list of internal hardcoded architecture specific directories to look in whether or not those directories exist, and regardless of the contents! By contrast use lib adds subdirectories based on a heuristic about their contents.	[reply] [d/l]
Re^4: PERL5LIB different than 'use lib' by almut (Canon) on May 08, 2009 at 09:53 UTC
Re^5: PERL5LIB different than 'use lib' by tilly (Archbishop) on May 08, 2009 at 13:58 UTC
Some notes below your chosen depth have not been shown here
Re: PERL5LIB different than 'use lib' by almut (Canon) on May 07, 2009 at 02:22 UTC
Just out of curiosity... you could compare the `strace` output you're getting with PERL5LIB against the corresponding attempt with `"use lib ..."`. If the one works and the other doesn't, there presumably is some difference in which places are being searched... `$ strace -efile perl -MSome::Module -e1 2>&1 \| grep Module` [download] (where Some::Module of course is a module that exhibits the difference)	[reply] [d/l] [select]
Re: PERL5LIB different than 'use lib' by Anonymous Monk on May 07, 2009 at 03:23 UTC
which, unfortunately, and contrary to the explanation in perlrun, isn't the same Yes it is, it is exactly the same. `D:\>perl -Mlib=TEST -le"print for @INC TEST D:/Perl/site/lib D:/Perl/lib . D:\>set PERL5LIB=TEST D:\>perl -le"print for @INC TEST D:/Perl/site/lib D:/Perl/lib .` [download] http://perl5.git.perl.org/perl.git/blob?f=lib/lib_pm.PL PERL5LIB mystery, PERL5LIB and Windows UNC Path, PERL5LIB-How does it work, Paths for PERL5LIB, the -I switch and 'use lib'.	[reply] [d/l]
Re^2: PERL5LIB different than 'use lib' by tilly (Archbishop) on May 07, 2009 at 23:34 UTC
See my response above to almut. While your Perl doesn't show it, mine shows a hardcoded difference in the behavior of PERL5LIB and use lib. And therefore there is every reason to believe saintmike's description.	[reply]