Respostas:
leia http://www.gnu.org/software/bash/manual/bashref.html#Bash-Startup-Files :
When Bash is invoked as an interactive login shell, or as a
non-interactive shell with the --login option, it first reads
and executes commands from the file /etc/profile, if that file
exists. After reading that file, it looks for ~/.bash_profile,
~/.bash_login, and ~/.profile, in that order, and reads and executes
commands from the first one that exists and is readable. The
--noprofile option may be used when the shell is started to inhibit
this behavior.
outras conchas carregam ~/.profile
também (zsh, tcsh) .. então, eu colocaria coisas do ambiente ~/.profile
.
atualização relacionada ao mac osx (obrigado @Matt B) :
para programas gui, leia http://developer.apple.com/library/mac/#qa/qa2001/qa1067.html e edite com ~/.MacOSX/environment.plist
cuidado.
~/.MacOSX/environment.plist
. Veja mais informações aqui: astro.washington.edu/users/rowen/AquaEnvVar.html .