sisyphus-sis@debian-sis:~/comp/$ cd ~/bleadperl/bin
sisyphus-sis@debian-sis:~/bleadperl/bin$ ln -s perl5.21.3 perl
sisyphus-sis@debian-sis:~/bleadperl/bin$ cd ~
sisyphus-sis@debian-sis:~$ which perl
/home/sisyphus-sis/bleadperl/bin/perl
sisyphus-sis@debian-sis:~$ perl -le 'print $^X;'
/usr/bin/perl
sisyphus-sis@debian-sis:~$ echo $PATH
/home/sisyphus-sis/bleadperl/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
sisyphus-sis@debian-sis:~$ perl5.21.3 -le 'print $^X;'
/home/sisyphus-sis/bleadperl/bin/perl5.21.3
sisyphus-sis@debian-sis:~$
####
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 $^X;'
/usr/bin/perl
##
##
sisyphus-sis@debian-sis:~/bleadperl/bin$ mv perl perl5.21.3
sisyphus-sis@debian-sis:~/bleadperl/bin$ cd ~
sisyphus-sis@debian-sis:~$ which perl
/usr/bin/perl
sisyphus-sis@debian-sis:~$ perl5.21.3 -le 'print $^X'
/home/sisyphus-sis/bleadperl/bin/perl5.21.3