Execing Processes in TypeScript

Here’s the translation of the Go code to TypeScript, along with explanations in Markdown format suitable for Hugo:

In the previous example, we looked at spawning external processes. We do this when we need an external process accessible to a running TypeScript process. Sometimes we just want to completely replace the current process with another one. To do this, we’ll use Node.js’s child_process.execFile function, which is similar to the classic exec function.

import { execFile } from 'child_process';

async function main() {
    // For our example we'll exec 'ls'. Node.js doesn't require an
    // absolute path to the binary we want to execute, so we can
    // use 'ls' directly.
    const binary = 'ls';

    // execFile requires arguments in array form (as opposed to
    // one big string). We'll give 'ls' a few common arguments.
    // Note that the first argument should be the program name.
    const args = ['-a', '-l', '-h'];

    try {
        // Here's the actual execFile call. If this call is
        // successful, it will return the stdout and stderr
        // of the executed command.
        const { stdout, stderr } = await execFile(binary, args);
        
        console.log('stdout:', stdout);
        console.log('stderr:', stderr);
    } catch (error) {
        console.error('Error:', error);
    }
}

main();

When we run our program, it will execute ls and display its output.

$ ts-node execing-processes.ts
stdout: total 16
drwxr-xr-x  4 user 136B Oct 3 16:29 .
drwxr-xr-x 91 user 3.0K Oct 3 12:50 ..
-rw-r--r--  1 user 1.3K Oct 3 16:28 execing-processes.ts

stderr:

Note that TypeScript (running on Node.js) doesn’t offer a direct equivalent to the Unix exec function that completely replaces the current process. The child_process.execFile function runs the command in a child process and returns its output. If you need to terminate the current process after executing another command, you would need to explicitly call process.exit() after the execFile call.

Also, TypeScript doesn’t have a direct equivalent to Go’s goroutines. For concurrent operations in TypeScript, you would typically use asynchronous functions with Promises or async/await syntax, or use Worker threads for CPU-intensive tasks.