blob: 0ce28d718e0cfc96cc356d9187fba1e3b65a25a4 (
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
25
26
27
28
29
30
31
32
33
34
35
36
|
# 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](https://doc.deno.land/builtin/stable#Deno.args) accesses the
command line arguments.
- [Deno.open](https://doc.deno.land/builtin/stable#Deno.open) is used to get a
handle to a file.
- [copy](https://doc.deno.land/https/deno.land/std@$STD_VERSION/io/util.ts#copy)
is used to transfer data from the file to the output stream.
- Files should be closed when you are finished with them
- Modules can be run directly from remote URLs.
## Example
In this program each command-line argument is assumed to be a filename, the file
is opened, and printed to stdout (e.g. the console).
```ts
/**
* cat.ts
*/
import { copy } from "https://deno.land/std@$STD_VERSION/io/util.ts";
for (const filename of Deno.args) {
const file = await Deno.open(filename);
await copy(file, Deno.stdout);
file.close();
}
```
To run the program:
```shell
deno run --allow-read https://deno.land/std@$STD_VERSION/examples/cat.ts /etc/passwd
```
|
