Default Env Variable as per the [docs](https://docs.aws.amazon.com/lambda/latest/dg/current-supported-versions.html#lambda-environment-variables):

```
NODE_PATH:/opt/nodejs/node8/node_modules/:/opt/nodejs/node_modules:$LAMBDA_RUNTIME_DIR/node_modules

```

I want to append my custom directory to it (NOT to override all)

```
NODE_PATH:$NODE_PATH:/opt/nodejs/mycustom-directory

```

I tried the above from lambda console it overrides all. `$NODE_PATH` is added as a string. It is not parsing `$NODE_PATH`

Output I got when printing env:

```
NODE_PATH=$NODE_PATH:/opt/nodejs/mycustom-directory

```

Similar Question but no Solution still: [AWS lambda add PATH variable?](https://stackoverflow.com/questions/47136472/aws-lambda-add-path-variable)