feat: allow writing to output file

[christf]

This allows to write the output to a file and closes #2418 . When calling jq inside a docker context this will be helpful as it means jq will not have to be called from within a shell with output redirection.

Caveats do apply:

• I have only started looking at the jq codebase today, so the code may be doing something insane

[christf]

Test on linux with utf-8:

✘-INT ~/Programmierung/jq [ofile|✚ 1…1]
19:42 $ echo '{ "foo": "💩" } '
{ "foo": "💩" }
✔ ~/Programmierung/jq [ofile|✚ 1…1]
19:42 $ echo '{ "foo": "💩" } ' | ./jq .
{
"foo": "💩"
}
✔ ~/Programmierung/jq [ofile|✚ 1…1]
19:42 $ echo '{ "foo": "💩" } ' | ./jq . -o foo
✔ ~/Programmierung/jq [ofile|✚ 1…1]
19:43 $ cat foo
{
"foo": "💩"
}
✔ ~/Programmierung/jq [ofile|✚ 1…1]
19:43 $

[wader]

There has been talks long time ago about adding adding -i/--inplace and jaq already supports it. Could that be an option? but one thing about how jq handles multiple inputs files, as they were concatenated, probably have be resolved in some way in that case.

$ echo -n 12 > a.json
$ echo -n 34 > b.json

$ jq . a.json b.json
1234

$ jaq . a.json b.json
12
34
$ jaq -i '.+1' a.json b.json
$ jaq . a.json b.json
13
35

[christf]

There has been talks long time ago about adding adding -i/--inplace and jaq already supports it. Could that be an option? but one thing about how jq handles multiple inputs files, as they were concatenated, probably have be resolved in some way in that case.

$ echo -n 12 > a.json
$ echo -n 34 > b.json

$ jq . a.json b.json
1234

$ jaq . a.json b.json
12
34
$ jaq -i '.+1' a.json b.json
$ jaq . a.json b.json
13
35

that is an interesting thought. In the use case I am hoping to solve, the output file needs to be in a certain place that is designed to hold only results. This is, what the tekton task specification might look like

- image: ghcr.io/jqlang/jq:1.9.0
  name: digest-to-results
  command:
    - jq -j '.[0].value' -o /tekton/results/IMAGE-DIGEST image-digested

[christf]

How can this best be progressed?