Runs a given command for each file in a folder, recursively; replaces #FILE_PATH, #FILE_NAME, #FILE_SIZE_KB in command (Deno)

args.ts

import * as fs from "https://deno.land/std@0.93.0/fs/mod.ts";
import * as path from "https://deno.land/std@0.93.0/path/mod.ts";

export default () => {
  let [execCmdTemplate, basedir = ".", fileExt = ""] = Deno.args;
  if (!execCmdTemplate) throw new Error("No command was given");
  if (!basedir || !fs.existsSync(basedir)) throw new Error("DIR doesn't exist");
  basedir = path.resolve(".", basedir);
  return { execCmdTemplate, basedir, fileExt };
}

index.ts

#!/usr/bin/env -S deno run --allow-all --unstable
// Runs a given command for each file in a folder, recursively
// Replaces #FILE_PATH, #FILE_NAME, #FILE_SIZE_KB in command
//$ deno run --allow-all --unstable https://gist.githubusercontent.com/crazy4groovy/52670e7a1c4be6537628b9bfb7b02d32/raw/index.ts 'echo #FILE_PATH::#FILE_NAME' ~ .jpg
import * as fs from "https://deno.land/std@0.93.0/fs/mod.ts";
import { exec } from "https://deno.land/x/exec@0.0.5/mod.ts";

import args from "./args.ts";

const { execCmdTemplate, basedir, fileExt } = args();

const validators = [
  (f: any) => Boolean(f.isFile),
  (f: any) => f.path?.endsWith(fileExt),
];

const replacers = {
  '#FILE_PATH': (f: any) => String(f.path),
  '#FILE_NAME': (f: any) => String(f.name),
  // check execCmdTemplate for calculating the "expensive" replacements:
  '#FILE_SIZE_KB': (
    execCmdTemplate.indexOf('#FILE_SIZE_KB') === -1 
      ? (f: any) => '#FILE_SIZE_KB' // not found
      : (f: any) => String(Math.round(Deno.statSync(f.path).size / 1024))),
} as Record<string, (f: any) => string>;

(async () => {
  for await (const f of fs.walkSync(basedir)) {
    const isValid = validators.find(v => !v(f)) === undefined; // i.e. check if found no falsies, then it's valid
    if (!isValid) continue;

    const cmd = Object.keys(replacers).reduce(
      (cmd: string, key: string) => cmd.replace(key, replacers[key](f)), 
      execCmdTemplate
    );
    await exec(cmd).catch(console.error);
  }
})();