I want to set an environment variable when running a program via child_process.exec. Is this possible?
I tried setting the env like this:
exec('FOO', {'FOO': 'ah'}, function(error, stdout, stderr) {console.log(stdout, stderr, error);});
but the resulting message said FOO did not exist.
You have to pass an options object that includes the key env whose value is itself an object of key value pairs.
exec('echo $FOO', {env: {'FOO': 'ah'}}, function (error, stdout, stderr)
{
console.log(stdout, stderr, error);
});
PATH that might otherwise exist. So, if you try to set an env variable and you suddenly get errors about the command you're trying to exec not being found, this is why. This isn't clear at all from the documentation and left me scratching my head for a bit. If you want to add env variables and stay platform-agnostic, you could make a copy of process.env, apply your changes to that, and pass it to child_process.exec.
process.env direclty. Ex: process.env["PATH"] += path.delimiter + process.cwd() + path.sep + "node_modules" + path.sep + ".bin"
env: { ...process.env, 'FOO': 'ah'}Based on @DanielSmedegaardBuus answer, you have to add your env var to the existing ones, if you want to preserve them:
const { exec } = require("child_process");
exec(
"echo $FOO",
{ env: { ...process.env, FOO: "ah" } },
function (error, stdout, stderr) {
console.log(stdout, stderr, error);
}
);
