sisyphus-sis@debian-sis:~/bleadperl/bin$ rm perl
sisyphus-sis@debian-sis:~/bleadperl/bin$ which perl
/usr/bin/perl
sisyphus-sis@debian-sis:~/bleadperl/bin$ mv perl5.21.3 perl
sisyphus-sis@debian-sis:~/bleadperl/bin$ which perl
/home/sisyphus-sis/bleadperl/bin/perl
sisyphus-sis@debian-sis:~/bleadperl/bin$ perl -le 'print $^X;'
/usr/bin/perl