Here is the result of trying to install DBI....

cpan[3]> install DBI
Running install for module 'DBI'
Running make for T/TI/TIMB/DBI-1.622.tar.gz
Fetching with LWP:
ftp://cpan.etla.org/pub/CPAN/authors/id/T/TI/TIMB/DBI-1.622.tar.gz
Warning (usually harmless): 'YAML' not installed, cannot parse '/var/r
+oot/.cpan/FTPstats.yml'

Warning (usually harmless): 'YAML' not installed, cannot parse '/var/r
+oot/.cpan/FTPstats.yml'

Fetching with LWP:
ftp://cpan.etla.org/pub/CPAN/authors/id/T/TI/TIMB/CHECKSUMS
Checksum for /var/root/.cpan/sources/authors/id/T/TI/TIMB/DBI-1.622.ta
+r.gz ok

  CPAN.pm: Going to build T/TI/TIMB/DBI-1.622.tar.gz

Your perl was compiled with gcc (version 4.2.1 (Based on Apple Inc. bu
+ild 5658) (LLVM build 2335.15.00)), okay.
Creating test wrappers for DBD::Gofer:
t/zvg_01basics.t 
t/zvg_02dbidrv.t 
.
.
.
Long list ..
.
.
t/zvxnp_52dbm_complex.t 
t/zvxnp_85gofer.t 
Creating test wrappers for DBD::Gofer + DBI::SQL::Nano + DBI::PurePerl
+:
t/zvxgnp_48dbi_dbd_sqlengine.t 
t/zvxgnp_49dbd_file.t 
t/zvxgnp_50dbm_simple.t 
t/zvxgnp_51dbm_file.t 
t/zvxgnp_52dbm_complex.t 
t/zvxgnp_85gofer.t 
Checking if your kit is complete...
Looks good

    I see you're using perl 5.012003 on darwin-thread-multi-2level, ok
+ay.
    Remember to actually *read* the README file!
    Use  'make' to build the software (dmake or nmake on Windows).
    Then 'make test' to execute self tests.
    Then 'make install' to install the DBI and then delete this workin
+g
    directory before unpacking and building any DBD::* drivers.

Writing Makefile for DBI
Can't exec "make": No such file or directory at /System/Library/Perl/5
+.12/CPAN/Distribution.pm line 2026.
  TIMB/DBI-1.622.tar.gz
  make -- NOT OK
Running make test
  Can't test without successful make
Running make install
  Make had returned bad status, install seems impossible
Failed during this command:
 TIMB/DBI-1.622.tar.gz                        : make NO

cpan[4]>
[download]

this is the same for all modules