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712 B
712 B
An implementation of the unix "cat" program
In this program each command-line argument is assumed to be a filename, the file is opened, and printed to stdout.
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();
}
The copy()
function here actually makes no more than the necessary kernel ->
userspace -> kernel copies. That is, the same memory from which data is read
from the file, is written to stdout. This illustrates a general design goal for
I/O streams in Deno.
Try the program:
deno run --allow-read https://deno.land/std/examples/cat.ts /etc/passwd