RE Go: Others have already mentioned the right way, thought I’d personally prefer ~/opt/go over what was suggested.

RE Perl: To instruct Perl to install to another directory, for example to ~/opt/perl5, put the following lines somewhere in your bash init files.

export PERL5LIB="$HOME/opt/perl5/lib/perl5${PERL5LIB:+:${PERL5LIB}}"
export PERL_LOCAL_LIB_ROOT="$HOME/opt/perl5${PERL_LOCAL_LIB_ROOT:+:${PERL_LOCAL_LIB_ROOT}}"
export PERL_MB_OPT="--install_base \"$HOME/opt/perl5\""
export PERL_MM_OPT="INSTALL_BASE=$HOME/opt/perl5"
export PATH="$HOME/opt/perl5/bin${PATH:+:${PATH}}"

Though you need to re-install the Perl packages you had previously installed.

The GNU GPL is not Mr. Nice Guy. It says no to some of the things that people sometimes want to do. There are users who say that this is a bad thing—that the GPL “excludes” some proprietary software developers who “need to be brought into the free software community.”

But we are not excluding them from our community; they are choosing not to enter. Their decision to make software proprietary is a decision to stay out of our community. Being in our community means joining in cooperation with us; we cannot “bring them into our community” if they don’t want to join.

You’ve probably already checked it out but make sure you’ve got only one of .profile, .bash_profile, .bashprofile. bash will only execute one of them in case there’s more than one (not sure which one off the top of my head.)