Running a stand-alone subcommand with zx

[p3k]

We are trying to combine CommanderJS and zx in subcommand and I noticed the zx extensions are not available then:

// foo.mjs (called by `zx ./foo.mjs info`)

#!/usr/bin/env zx

import { program } from "commander/esm.mjs";

program.command("info", "output information").alias("i")

// foo-info.mjs

#!/usr/bin/env zx

console.log(typeof $);
// undefined

As a work-around we certainly could import the extensions again (e.g. with import { $ } from "zx") but it feels a bit redundant and wrong.

Is there an option to run a stand-alone subcommand with the correct binary? Or make CommanderJS respect the shebang #!/usr/bin/env zx?

[shadowspawn]

If you make foo-info.mjs executable and remove the file extension, then the file will be executed directly and the shebang will apply. (This does not work on Windows.)

// foo-info
#!/usr/bin/env zx

console.log(typeof $);

% zx foo.mjs i
function

If the file has a source extension then process.argv[0] is used to process it, which is node in this case.

const sourceExt = ['.js', '.ts', '.tsx', '.mjs', '.cjs'];

[p3k]

great, that works! thanks for the explanation, @shadowspawn

the only downside seems to be missing syntax highlighting due to the undefined file extension for editors…

[shadowspawn]

For interest...

Commander expects by default that argv[0] is the utility, argv[1] is the script name, and argv[2] is the first of the user supplied arguments.

• https://nodejs.org/dist/latest-v16.x/docs/api/process.html#process_process_argv

But when launched by zx there is an extra argument which is zx itself.

// foo.mjs
console.log(process.argv);

% zx foo.mjs install
[ '/usr/local/bin/node', '/usr/local/bin/zx', 'foo.mjs', 'install' ]

I think if zx replaced the node argument instead of adding afterwards, Commander would work ok with the file extension.

[p3k]

I think if zx replaced the node argument instead of adding afterwards, Commander would work ok with the file extension.

good point. maybe this is due to zx being an npm module run by node, anyway…?

does this mean, i could tamper with the argv array myself and make this work somehow?

[shadowspawn]

If you can modify process.argv, yes. But is it read-only in esm?

[p3k]

If you can modify process.argv, yes. But is it read-only in esm?

looking good, e.g.

console.log(process.argv.length) // 4
process.argv.shift();
console.log(process.argv.length) // 3

[p3k]

and now zx works with scripts having file extension, too! awesome.

[shadowspawn]

An answer was provided, and no further activity in a month. Closing this as resolved.

Feel free to open a new issue if it comes up again, with new information and renewed interest.