Environment variables

Some places to look at to define/change variables, and which contents to expect.

Global

/etc/environment
global variables: HTTP(S) & SOCKS proxies, custom PATH

Session

/etc/profile
default session variables
/etc/profile.d/*.sh
extra session variables
~/.xprofile
user-defined X11 settings -mostly for lightweight session managers (i3, awesome-wm, etc.)
~/.profile
user-defined variables -superseded by ~/.bash_profile

Bash

/etc/bash.bashrc
default Bash settings
~/.bash_profile
user-defined Bash settings -mostly for X11/startup stuff
~/.bashrc
user-defined Bash configuration (main file)
~/.bash_aliases
user-defined Bash command aliases and functions

Superusers

/etc/login.defs
console & login configuration
/etc/sudoers
sudoers configuration -always use visudo to edit!

SSH

/etc/ssh/sshd_config
server-side, can allow the client to pass variables
/etc/ssh/ssh_config
client-side, can send variables to servers

SaltStack

/etc/default/salt-minion (deprecated in recent versions)
can be used to source /etc/environment -not always included in the distro’s packages
/etc/salt/minion
HTTP(S) proxy configuration