blob: efec9e3fb3f23a43e0c50253d41518001c1e1119 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
|
## 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.
```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();
}
```
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:
```shell
deno run --allow-read https://deno.land/std@$STD_VERSION/examples/cat.ts /etc/passwd
```
|
