systemd environment.d 5 environment.d Definition of user service environment ~/.config/environment.d/*.conf /etc/environment.d/*.conf /run/environment.d/*.conf /usr/lib/environment.d/*.conf /etc/environment Configuration files in the environment.d/ directories contain lists of environment variable assignments for services started by the systemd user instance. systemd-environment-d-generator8 parses them and updates the environment exported by the systemd user instance. See below for an discussion of which processes inherit those variables. It is recommended to use numerical prefixes for file names to simplify ordering. For backwards compatibility, a symlink to /etc/environment is installed, so this file is also parsed. The configuration files contain a list of KEY=VALUE environment variable assignments, separated by newlines. The right hand side of these assignments may reference previously defined environment variables, using the ${OTHER_KEY} and $OTHER_KEY format. It is also possible to use ${FOO:-DEFAULT_VALUE} to expand in the same way as ${FOO} unless the expansion would be empty, in which case it expands to DEFAULT_VALUE, and use ${FOO:+ALTERNATE_VALUE} to expand to ALTERNATE_VALUE as long as ${FOO} would have expanded to a non-empty value. No other elements of shell syntax are supported. Each KEY must be a valid variable name. Empty lines and lines beginning with the comment character # are ignored. /etc/environment.d/60-foo.conf: FOO_DEBUG=force-software-gl,log-verbose PATH=/opt/foo/bin:$PATH LD_LIBRARY_PATH=/opt/foo/lib${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH} XDG_DATA_DIRS=/opt/foo/share:${XDG_DATA_DIRS:-/usr/local/share/:/usr/share/} Environment variables exported by the user manager (systemd --user instance started in the user@uid.service system service) apply to any services started by that manager. In particular, this may include services which run user shells. For example in the GNOME environment, the graphical terminal emulator runs as the gnome-terminal-server.service user unit, which in turn runs the user shell, so that shell will inherit environment variables exported by the user manager. For other instances of the shell, not launched by the user manager, the environment they inherit is defined by the program that starts them. Hint: in general, systemd.service5 units contain programs launched by systemd, and systemd.scope5 units contain programs launched by something else. Specifically, for ssh logins, the sshd8 service builds an environment that is a combination of variables forwarded from the remote system and defined by sshd, see the discussion in ssh1. A graphical display session will have an analogous mechanism to define the environment. Note that some managers query the systemd user instance for the exported environment and inject this configuration into programs they start, using systemctl show-environment or the underlying D-Bus call. systemd1, systemd-environment-d-generator8, systemd.environment-generator7