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node.jslinuxbashshellzsh

Bash export variables but only for current command

I want to load some environment variables from a file before running a node script, so that the script has access to them. However, I don't want the environment variables to be set in my shell after the script is done executing.

I can load the environment variables like this:

export $(cat app-env-vars.txt | xargs) && node my-script.js

However, after the command is run, all of the environment variables are now set in my shell.

I'm asking this question to answer it, since I figured out a solution but couldn't find an answer on SO.

Solution

  • If you wrap the command in parentheses, the exports will be scoped to within those parens and won't pollute the global shell namespace:

    (export $(cat app-env-vars.txt | xargs) && node my-script.js)

    Echo'ing one of the environment variables from the app.env file after executing the command will show it as empty.