Setting system-wide environment variables on RedHat-based machines

I keep forgetting this, so I'm committing it to long-term memory. If you have a RedHat-based operating system (RH, CentOS etc) and you need to set certain environment variables so they're available to every user, one good place to do it is to drop a script ending in .sh in /etc/profile.d. Then export your desired environment variables there.

Here's an example from a CentOS machine I have:

# cd /etc/profile.d
# cat java.sh 
export JAVA_HOME=/usr/java/default

Note that you can do whatever else you need in these scripts -- for example you can set up aliases etc. Every script in /etc/profile.d which ends in .sh gets sourced in /etc/profile.