Enviroment variables using fish shell
Sometimes we need to export some value as an
env var (eg. android sdk path). It is important to know how to do this well for smooth system administration.
Each shell has its own way to manage environment, I’m using fish shell.
In order to list current vars, standard
env command is available.
Local env vars
We could run an app with custom enviroment vars, like this:
env LALA='foo bar' some_cmd
This does not always work, because
env bypasses our shell.
In those situations, we could use
set -lx LALA='foo bar'; some_cmd
-l switch means local scope, the variable is temporal.
Persistent env vars
When we need env vars to be persistent only across a session, we use
global ones (
set -gx LALA='foo bar' some_cmd other_cmd
Finally, we could use
universal env vars, which are fully persistent across multiple sessions (
For example, I used them in order to configure android sdk, like this:
set -U ANDROID_HOME /path/to/android/sdk
Universal env vars are persistent across reboots, you can inspect them using
set -U cmd.
PATH env var is an special case. We cannot modify it directly, because it could be overwritten by the shell.
In order to overcome this situation, fish provides the
fish_user_paths variable, which is automatically merged to
We could add some custom bin directory (e.g. node_modules bin dir), like this:
set -U fish_user_paths $fish_user_paths /path/to/node_modules/bin
In this way we preserve previously added paths, and the new dir is only appended to
The shell automatically adds the custom paths to the
PATH var each time a session is started.