Linux Shell Environment Setup Using /etc/profile.d/*
When a user logs in, environment variables are set from various places. That includes:
/etc/profile (for all users).
Then all the files in the /etc/profile.d directory.
/etc/profile.d/ is a good place to put your application specific setups. For example, I always use SSH for CVS (cf. RSH). So I use:
echo "export CVS_RSH=ssh" >> /etc/profile.d/cvs.sh
chmod +x /etc/profile.d/cvs.sh