# bibfetch

What a catalogue says about an identifier, asked of the body that assigns it.

Part of [catena](../../README.md).

## What it does

[`idnorm`](../idnorm/README.md) can tell you a DOI is well formed. It cannot
tell you the paper exists — that is not a fact about the string, it is a fact
about the world, and the only way to learn it is to ask somebody who keeps a
register.

So this asks, and that is the only thing it does.

## When you would use it

- **Auditing a bibliography.** A well-formed DOI that no register has is a
  mistyped one, and a catalogue can carry it for years without noticing.
- **Filling in a reference** you have only the identifier for.
- **Before citing something**, to check the year and the authors are what you
  think they are.

## Install

```sh
cargo install --git https://git.pumpin.online/funkpower/catena bibfetch
```

## Example

```
$ printf '10.1093/mind/LIX.236.433\narXiv:2401.01234\n978-0-306-40615-7\n' | idnorm | bibfetch --polite you@example.org
{"v":1,"id":"10.1093/mind/lix.236.433","kind":"doi","found":true,"source":"crossref","title":"I.—COMPUTING MACHINERY AND INTELLIGENCE","authors":["A. M. TURING"],"year":1950,"container":"Mind"}
{"v":1,"id":"2401.01234","kind":"arxiv","found":true,"source":"arxiv","title":"Mixture cure semiparametric additive hazard models under partly interval censoring -- a penalized likelihood approach","authors":["Jinqing Li","Jun Ma"],"year":2024,"container":"arXiv","summary":"Survival analysis can sometimes involve individuals who will not experience…"}
{"v":1,"id":"9780306406157","kind":"isbn","found":true,"source":"openlibrary","title":"Error-correction coding for digital communications","year":1981,"container":"Plenum Press"}
```

The ones nobody has:

```
$ printf '10.9999/definitely-not-a-real-doi\n' | idnorm | bibfetch
{"v":1,"id":"10.9999/definitely-not-a-real-doi","kind":"doi","found":false,"source":"crossref"}
$ echo $?
1
```

Absence is the useful answer here. It is what tells a catalogue that a DOI it
has been carrying for three years was mistyped on the way in.

Auditing a whole bibliography:

```sh
idnorm --quiet refs.txt | bibfetch --polite you@example.org \
  | jq -r 'select(.found | not) | "missing: \(.id)"'
```

## Options

| Option | Effect |
|---|---|
| `--polite <EMAIL>` | An address to put in the request. The registers ask for one and answer faster when they get it |
| `--timeout <SECONDS>` | How long to wait on a register. Default `20` |
| `--attempts <COUNT>` | How many times to ask before believing a failure. Default `3` |
| `--man` | Write this page as a manual page, in roff |

## Exit codes

| Code | Meaning |
|---|---|
| `0` | Every identifier was found |
| `1` | At least one was not |
| `64` | The command line was wrong |
| `65` | The input was not identifier records |
| `69` | A register could not be reached |
| `74` | The file could not be read |

Exit `1` is an answer — the register replied and does not have it. Exit `69`
is a failure — nobody replied, and the identifier may be perfectly good.

## The registers

| Kind | Asked of | Why that one |
|---|---|---|
| `doi` | Crossref | It assigns most scholarly DOIs |
| `arxiv` | the arXiv | Its own register of preprints |
| `isbn` | OpenLibrary | Books, without a key |

An **ISSN** has no register that answers without a key, so it is not looked up
on its own. A journal's ISSN comes back on the works published in it instead.

A failure is retried, waiting a second and then two: long enough for a
register that is rate-limiting, short enough that one which is simply down
does not hold up a pipeline. An answer this cannot read is not retried,
because it will not read any better next time.

## Reaching the network

This and [`emb`](../emb/README.md) are the only two tools here that do. Both
say so in `--help`, and for both it is the whole of what they do rather than
something that happens on the way to something else — which is the condition
under which [the contract](../../docs/contract.md) allows it at all.

Nothing is cached, nothing is stored, and nothing is sent but the identifier
and the address you pass to `--polite`.

## See also

- [`idnorm`](../idnorm/README.md) — reading the identifier in the first place.
- [`bibclean`](../bibclean/README.md) — the rest of a catalogue record.