🔀 Cross platform setting of environment scripts
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cross-env 🔀
Run scripts that set and use environment variables across platforms
The problem
Most Windows command prompts will choke when you set environment variables with
NODE_ENV=productionlike 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:
$ENV_VARand on windows you use
%ENV_VAR%.
This solution
cross-envmakes 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-envwill take care of setting it properly.
- Installation
- Usage
cross-env
vscross-env-shell
- Windows Issues
- Inspiration
- Other Solutions
- Contributors
- LICENSE
Installation
This module is distributed via npm which is bundled with node and should be installed as one of your project's
devDependencies:
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
NOTE : Version 7 of cross-env only supports Node.js 10 and higher, to use it on Node.js 8 or lower install version 6
npm install --save-dev [email protected]
Usage
I use this in my npm scripts:
{
"scripts": {
"build": "cross-env NODE_ENV=production webpack --config build/webpack.config.js"
}
}
Ultimately, the command that is executed (using
cross-spawn) is:
webpack --config build/webpack.config.js
The
NODE_ENVenvironment variable will be set by
cross-env
You can set multiple environment variables at a time:
{
"scripts": {
"build": "cross-env FIRST_ENV=one SECOND_ENV=two node ./my-program"
}
}
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:
{
"scripts": {
"parentScript": "cross-env GREET=\"Joe\" npm run childScript",
"childScript": "cross-env-shell \"echo Hello $GREET\""
}
}
Where
childScriptholds the actual command to execute and
parentScriptsets 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
$GREETenv var syntax even on Windows which would usually require it to be
%GREET%.
If you precede a dollar sign with an odd number of backslashes the expression statement will not be replaced. Note that this means backslashes after the JSON string escaping took place.
"FOO=\\$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:
{
"scripts": {
"test": "cross-env TS_NODE_COMPILER_OPTIONS={\\\"module\\\":\\\"commonjs\\\"} node some_file.test.ts"
}
}
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
vs cross-env-shell
The
cross-envmodule exposes two bins:
cross-envand
cross-env-shell. The first one executes commands using
cross-spawn, while the second one uses the
shelloption from Node's
spawn.
The main use case for
cross-env-shellis when you need an environment variable to be set across an entire inline shell script, rather than just one command.
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-shellinstead of
cross-env.
{
"scripts": {
"greet": "cross-env-shell GREETING=Hi NAME=Joe \"echo $GREETING && echo $NAME\""
}
}
The rule of thumb is: if you want to pass to
cross-enva command that contains special shell characters that you want interpreted, then use
cross-env-shell. Otherwise stick to
cross-env.
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
SIGINTevent invoked by pressing
Ctrl + Con the command-line interface.
Windows Issues
Please note that
npmuses
cmdby default and that doesn't support command substitution, so if you want to leverage that, then you need to update your
.npmrcto set the
script-shellto powershell. Learn more here.
Inspiration
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.
Other Solutions
-
env-cmd
- Reads environment variables from a file instead -
@naholyr/cross-env
-cross-env
with support for setting default values
Contributors
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
CONTRIBUTING.md
LICENSE
MIT