Re: What is cpan (the installer) doing prepending all these directories to the PERL5LIB path?

I'm following up to myself again. I haven't discovered exactly why this is happening but it has inflated greatly.

Prepending blib/arch and blib/lib of 28 build dirs to PERL5LIB, reaching size 4443; for 'get'
…
Prepending blib/arch and blib/lib of 28 build dirs to PERL5LIB, reaching size 4443; for 'prepare'
…
Prepending blib/arch and blib/lib of 28 build dirs to PERL5LIB, reaching size 4443; for 'make'
…
Prepending blib/arch and blib/lib of 28 build dirs to PERL5LIB, reaching size 4443; for 'test'

I'm doggedly determined to figure this out but others matters have intervened. I know more than a few people would say that the answer is use cpanm and it's not a bad answer; I have been using canpm some of the time. See my previous self-reply above for details on what I've looked at so far.

– Soren
Feb 23, 2026 at 17:12 UTC

I anticipate that some readers will want the entire context. Here it is tucked into READMORE:

$ cpan
cpan> test Sub::Exporter::Lexical
CPAN: Term::ANSIColor loaded ok (v5.01)
CPAN: HTTP::Tiny loaded ok (v0.092)
CPAN: Net::SSLeay loaded ok (v1.94)
CPAN: IO::Socket::SSL loaded ok (v2.098)
Fetching with HTTP::Tiny:
https://cpan.org/authors/01mailrc.txt.gz
Reading 'C:/Users/somia/AppData/strawberry-perl-sourcecache/authors/01
+mailrc.txt.gz'
CPAN: Compress::Zlib loaded ok (v2.213)
CPAN: YAML::XS loaded ok (vv0.902.0)
Reading 123 yaml files from /cygdrive/C/Users/somia/cygwin-perl-cpan/b
+uild/
..............................................................DONE
Restored the state of 28 (in 1.5971 secs)
......................................................................
+......DONE
Fetching with HTTP::Tiny:
https://cpan.org/modules/02packages.details.txt.gz
Reading 'C:/Users/somia/AppData/strawberry-perl-sourcecache/modules/02
+packages.details.txt.gz'
  Database was generated on Mon, 23 Feb 2026 09:53:03 GMT
CPAN: HTTP::Date loaded ok (v6.06)
......................................................................
+......DONE
Fetching with HTTP::Tiny:
https://cpan.org/modules/03modlist.data.gz
Reading 'C:/Users/somia/AppData/strawberry-perl-sourcecache/modules/03
+modlist.data.gz'
DONE
Running test for module 'Sub::Exporter::Lexical'
CPAN: CPAN::Kwalify loaded ok (v5.50)
Prepending blib/arch and blib/lib of 28 build dirs to PERL5LIB, reachi
+ng size 4443; for 'get'
Fetching with HTTP::Tiny:
https://cpan.org/authors/id/R/RJ/RJBS/Sub-Exporter-Lexical-1.001.tar.g
+z
CPAN: Digest::SHA loaded ok (v6.04)
Fetching with HTTP::Tiny:
https://cpan.org/authors/id/R/RJ/RJBS/CHECKSUMS
Checksum for C:/Users/somia/AppData/strawberry-perl-sourcecache/author
+s/id/R/RJ/RJBS/Sub-Exporter-Lexical-1.001.tar.gz ok
CPAN: Archive::Tar loaded ok (v3.04)
Sub-Exporter-Lexical-1.001
Sub-Exporter-Lexical-1.001/README
Sub-Exporter-Lexical-1.001/Changes
Sub-Exporter-Lexical-1.001/LICENSE
Sub-Exporter-Lexical-1.001/dist.ini
Sub-Exporter-Lexical-1.001/META.yml
Sub-Exporter-Lexical-1.001/MANIFEST
Sub-Exporter-Lexical-1.001/t
Sub-Exporter-Lexical-1.001/t/basic.t
Sub-Exporter-Lexical-1.001/META.json
Sub-Exporter-Lexical-1.001/snippet.pl
Sub-Exporter-Lexical-1.001/Makefile.PL
Sub-Exporter-Lexical-1.001/t/lib
Sub-Exporter-Lexical-1.001/t/lib/TestExporter.pm
Sub-Exporter-Lexical-1.001/t/00-report-prereqs.t
Sub-Exporter-Lexical-1.001/xt/author
Sub-Exporter-Lexical-1.001/xt/author/pod-syntax.t
Sub-Exporter-Lexical-1.001/t/00-report-prereqs.dd
Sub-Exporter-Lexical-1.001/xt/author/00-compile.t
Sub-Exporter-Lexical-1.001/lib/Sub/Exporter
Sub-Exporter-Lexical-1.001/lib/Sub/Exporter/Lexical.pm
Sub-Exporter-Lexical-1.001/xt/release
Sub-Exporter-Lexical-1.001/xt/release/changes_has_content.t
Prepending blib/arch and blib/lib of 28 build dirs to PERL5LIB, reachi
+ng size 4443; for 'prepare'
CPAN: CPAN::Meta::Requirements loaded ok (v2.143)
CPAN: Parse::CPAN::Meta loaded ok (v2.150010)
CPAN: CPAN::Meta loaded ok (v2.150010)
CPAN: Module::CoreList loaded ok (v5.20250820)
Configuring R/RJ/RJBS/Sub-Exporter-Lexical-1.001.tar.gz with Makefile.
+PL
CPAN: CPAN::Reporter loaded ok (v1.2020)
Checking if your kit is complete...
Looks good
Generating a Unix-style Makefile
Writing Makefile for Sub::Exporter::Lexical
Writing MYMETA.yml and MYMETA.json
(/usr/bin/perl Makefile.PL exited with 0)
CPAN::Reporter: Makefile.PL result is 'pass', No errors.
  RJBS/Sub-Exporter-Lexical-1.001.tar.gz
  /usr/bin/perl Makefile.PL -- OK
Running make for R/RJ/RJBS/Sub-Exporter-Lexical-1.001.tar.gz
Prepending blib/arch and blib/lib of 28 build dirs to PERL5LIB, reachi
+ng size 4443; for 'make'
cp lib/Sub/Exporter/Lexical.pm blib/lib/Sub/Exporter/Lexical.pm
cp snippet.pl blib/lib/Sub/Exporter/snippet.pl
Manifying 1 pod document
(C:/ix/cygwin/bin/make exited with 0)
CPAN::Reporter: make result is 'pass', No errors.
  RJBS/Sub-Exporter-Lexical-1.001.tar.gz
  C:/ix/cygwin/bin/make -- OK
Prepending blib/arch and blib/lib of 28 build dirs to PERL5LIB, reachi
+ng size 4443; for 'test'
CPAN: CPAN::DistnameInfo loaded ok (v0.12)
Running make test for RJBS/Sub-Exporter-Lexical-1.001.tar.gz
PERL_DL_NONLAZY=1 "/usr/bin/perl.exe" "-MExtUtils::Command::MM" "-MTes
+t::Harness" "-e" "undef *Test::Harness::Switches; test_harness(0, 'bl
+ib/lib', 'blib/arch')" t/*.t
#
# Versions for all modules listed in MYMETA.json (including optional o
+nes):
#
# === Configure Requires ===
#
#     Module              Want Have
#     ------------------- ---- ----
#     ExtUtils::MakeMaker 6.78 7.74
#
# === Build Requires ===
#
#     Module              Want Have
#     ------------------- ---- ----
#     ExtUtils::MakeMaker  any 7.74
#
# === Test Requires ===
#
#     Module              Want     Have
#     ------------------- ---- --------
#     ExtUtils::MakeMaker  any     7.74
#     File::Spec           any     3.91
#     Test::More          0.96 1.302219
#     lib                  any     0.65
#     strict               any     1.13
#
# === Test Recommends ===
#
#     Module         Want     Have
#     ---------- -------- --------
#     CPAN::Meta 2.120900 2.150010
#
# === Runtime Requires ===
#
#     Module         Want     Have
#     ------------- ----- --------
#     Sub::Exporter 0.978    0.991
#     perl          5.012 5.040003
#     warnings        any     1.70
#
t/00-report-prereqs.t .. ok
Built-in function 'builtin::export_lexically' is experimental at /cygd
+rive/C/Users/somia/cygwin-perl-cpan/build/Sub-Exporter-Lexical-1.001-
+0/blib/lib/Sub/Exporter/Lexical.pm line 134.
t/basic.t .............. ok
All tests successful.
Files=2, Tests=4,  8 wallclock secs ( 0.11 usr  0.53 sys +  0.86 cusr 
+ 6.84 csys =  8.34 CPU)
Result: PASS
(C:/ix/cygwin/bin/make test exited with 0)
CPAN::Reporter: Test result is 'pass', All tests successful.
CPAN::Reporter: preparing a CPAN Testers report for Sub-Exporter-Lexic
+al-1.001
CPAN::Reporter: sending test report with 'pass' via Metabase
No history written (no histfile specified).
Lockfile removed.
  RJBS/Sub-Exporter-Lexical-1.001.tar.gz
  C:/ix/cygwin/bin/make test -- OK

cpan>
[download]

Comment on Re: What is cpan (the installer) doing prepending all these directories to the PERL5LIB path? Download Code

Replies are listed 'Best First'.
Re^2: What is cpan (the installer) doing prepending all these directories to the PERL5LIB path? by choroba (Cardinal) on Feb 23, 2026 at 17:48 UTC
See is_tested: is_tested List all build directories of distributions that have been tested successfully but have not yet been installed. See also install_tested. So it seems you are testing modules without installing them. `map{substr$_->[0],$_->[1]\|\|0,1}[\\|\|{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^ARGV,3]`	[reply] [d/l]
Re^3: What is cpan (the installer) doing prepending all these directories to the PERL5LIB path? by ikegami (Patriarch) on Feb 24, 2026 at 14:38 UTC
It's the modules that were tested but not installed during a session. At least according to my testing, the list isn't persistent. Exiting the shell resets the list. This also means it doesn't apply to `cpan -t MODULE`	[reply] [d/l]