An implementation of the unix “cat” program

Concepts

• Use the Deno runtime API to output the contents of a file to the console.
• Deno.args accesses the command line arguments.
• Deno.open is used to get a handle to a file.
• Deno.copy is used to transfer data from the file to the output stream.
• Files should be closed when you are finished with them
• Modules can be run directly from remote URLs.

Example

In this program each command-line argument is assumed to be a filename, the file is opened, and printed to stdout (e.g. the console).

`

/** * cat.ts */for (let i = 0; i < Deno.args.length; i++) {  const filename = Deno.args[i];  const file = await Deno.open(filename);  await Deno.copy(file, Deno.stdout);  file.close();}

`

To run the program:

`

deno run --allow-read https://deno.land/std@0.79.0/examples/cat.ts /etc/passwd

`