Run scripts that set and use environment variables across platforms
Most Windows command prompts will choke when you set environment variables with
NODE_ENV=production like that. (The exception is Bash on Windows,
which uses native Bash.) Similarly, there's a difference in how windows and
POSIX commands utilize environment variables. With POSIX, you use:
and on windows you use
cross-env makes it so you can have a single command without worrying about
setting or using the environment variable properly for the platform. Just set it
like you would if it's running on a POSIX system, and
cross-env will take care
of setting it properly.
npm install --save-dev cross-env
WARNING! Make sure that when you're installing packages that you spell things correctly to avoid mistakenly installing malware
I use this in my npm scripts:
Ultimately, the command that is executed (using
webpack --config build/webpack.config.js
NODE_ENV environment variable will be set by
You can also split a command into several ones, or separate the environment variables declaration from the actual command execution. You can do it this way:
childScript holds the actual command to execute and
the environment variables to use. Then instead of run the childScript you run
the parent. This is quite useful for launching the same command with different
env variables or when the environment variables are too long to have everything
in one line. It also means that you can use
$GREET env var syntax even on
Windows which would usually require it to be
If you preceed a dollar sign with an odd number of backslashes the expression statement will not be replaced. Note that this means backslashes after the JSON string escaping took place.
"FOO=\\$BAR" will not be replaced.
"FOO=\\\\$BAR" will be replaced though.
Lastly, if you want to pass a JSON string (e.g., when using ts-loader), you can do as follows:
Pay special attention to the triple backslash
(\\\) before the double quotes
(") and the absence of single quotes
Both of these conditions have to be met in order to work both on Windows and UNIX.
cross-env module exposes two bins:
first one executes commands using
cross-spawn, while the
second one uses the
shell option from Node's
The main use case for
cross-env-shell is when you need an environment
variable to be set across an entire inline shell script, rather than just one
For example, if you want to have the environment variable apply to several
commands in series then you will need to wrap those in quotes and use
cross-env-shell instead of
The rule of thumb is: if you want to pass to
cross-env a command that
contains special shell characters that you want interpreted, then use
cross-env-shell. Otherwise stick to
On Windows you need to use
cross-env-shell, if you want to handle signal events inside of your program. A common case for that is when you want to capture a
SIGINT event invoked by pressing
Ctrl + C on the command-line interface.
I originally created this to solve a problem I was having with my npm scripts in angular-formly. This made contributing to the project much easier for Windows users.
env-cmd- Reads environment variables from a file instead
Thanks goes to these people (emoji key):
This project follows the all-contributors specification. Contributions of any kind welcome!
Note: this was added late into the project. If you've contributed to this project in any way, please make a pull request to add yourself to the list by following the instructions in the