[BUG] npx with option -c doesn't work as expected in gitbash on windows

[mofterdinger]

What / Why

Hi,

I try to use npx with option -c in a gitbash on windows to execute a command provided by an npm module, but npx tells me that the command wasn't found. The same command line works fine on Mac/Linux.

This is the command I try to execute: npx -c 'cds version'.
The npm module is: @sap/cds-dk

I'm using the following versions:

• npx: 6.14.8
• node: v12.16.3
• gitbash: 1.9.5

When

Each time I execute the command line: npx -c 'cds version'

Where

• n/a

How

Current Behavior

The command npx without option -c works fine, but we want to have a npm run-script-like shell environment.

Steps to Reproduce

Inside a gitbash on windows follow these steps to reproduce:

• create an empty directory and cd into it
• call npm init
• call npm install @sap/cds-dk
• call npx -c 'cds version'
  --> you get error:
  'cds' is not recognized as an internal or external command, operable program or batch file.

Expected Behavior

See this console output with version information:

@sap/cds: 4.1.7
@sap/cds-compiler: 1.35.0
@sap/cds-dk: 2.0.8
@sap/cds-foss: 2.0.0
@sap/cds-reflect: 2.12.2
@sap/cds-runtime: 2.1.7
Node.js: v12.16.3
home: c:\Users\d032842\workspaces\playground\testnpx\node_modules\@sap\cds-dk\node_modules\@sap\cds
testnpx: 1.0.0

Who

• n/a

References

• n/a

[mofterdinger]

Hi,
is someone able to reproduce this issue and can tell me, if this is an issue in npx or do I use it the wrong way?
Thanks,
Markus

[beckermarc]

I was able to find the root cause of this issue, but I am unsure how this can be fixed in npx/npm.
The reason any npx -c command doesn't work in git-bash or any other cygwin bash is, that npx is getting a Unix-like environment from npm run env, even though it will execute the command by default within a standard windows cmd shell.

In case of the option -c npx creates a node run-script like environment using npm run env (code). The environment returned from this process is later set in the npx process environment (code).
Using that environment a new process is spawned later on using child_process.spawn, on Windows this always runs inside a new shell (code), which by default is given by process.env.COMSPEC, which usually is set to cmd.exe.

However the environment returned by npm run env is not a valid environment for a cmd.exe windows process, as when it is executed inside a git-bash it returns a Unix-style PATH environment variable, which leads to the command not found error mentioned in the issue.
The npm run env returns such a PATH environment variable, because of the special handling for cygwin and git-bash shells on Windows, which can be seen here and ultimately here.

The npx command therefore executes successfully, when removing the environment variables MSYSTEM and TERM.
Therefore MSYSTEM= TERM= npx -c 'cds version' runs successfully, while npx -c 'cds version' fails.

Another possibility to fix this issue, is to prevent npx to let child_process.spawn pick the cmd.exe as shell, but explicitly pass option -s "C:\Program Files\Git\bin\bash.exe" to ensure that the git bash is also used as shell by npx, which then again fits the Unix-style PATH environment variable. Unfortunately setting the npm config option script-shell (reference) does not seem to be considered by npx. This could however help to override the default in such an environment.

I guess therefore there are two main issues at play here. The first is that npx and child_process.spawn assume a Windows-like environment if only process.platform === 'win32', while npm run env seems to consider the environment variables MSYSTEM and TERM as well. The other issue is that npx does not consider NPMs configuration option script-shell.