---
name: "URI::Heuristic"
section: "3pm"
platform: "linux"
package: "perl-uri"
version: "5.40-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/URI::Heuristic"
---

# URI::Heuristic(3pm)

Expand URI using heuristics

## NAME

URI::Heuristic - Expand URI using heuristics

## SYNOPSIS

```
 use URI::Heuristic qw(uf_uristr);
 $u = uf_uristr("example");          # http://www.example.com
 $u = uf_uristr("www.sol.no/sol");   # http://www.sol.no/sol
 $u = uf_uristr("aas");              # http://www.aas.no
 $u = uf_uristr("ftp.funet.fi");     # ftp://ftp.funet.fi
 $u = uf_uristr("/etc/passwd");      # file:/etc/passwd
```

## DESCRIPTION

This module provides functions that expand strings into real absolute URIs using some built-in heuristics.  Strings that already represent absolute URIs (i.e. that start with a `"scheme:"` part) are never modified and are returned unchanged.  The main use of these functions is to allow abbreviated URIs similar to what many web browsers allow for URIs typed in by the user.

The following functions are provided:

- uf\_uristr($str)

  Tries to make the argument string into a proper absolute URI string.  The "uf\_" prefix stands for "User  Friendly".  Under MacOS, it assumes that any string with a common URL  scheme (http, ftp, etc.) is a URL rather than a local path.  So don't name  your volumes after common URL schemes and expect **uf\_uristr()** to construct  valid file: URL's on those volumes for you, because it won't.

- uf\_uri($str)

  Works the same way as **uf\_uristr()** but returns a `"URI"` object.

## ENVIRONMENT

If the hostname portion of a URI does not contain any dots, then certain qualified guesses are made.  These guesses are governed by the following environment variables:

- COUNTRY

  The two-letter country code (ISO 3166) for your location.  If the domain name of your host ends with two letters, then it is taken to be the default country. See also Locale::Country.

- HTTP\_ACCEPT\_LANGUAGE, LC\_ALL, LANG

  If COUNTRY is not set, these standard environment variables are examined and country (not language) information possibly found in them is used as the default country.

- URL\_GUESS\_PATTERN

  Contains a space-separated list of URL patterns to try.  The string "ACME" is for some reason used as a placeholder for the host name in the URL provided.  Example:

  ```
   URL_GUESS_PATTERN="www.ACME.no www.ACME.se www.ACME.com"
   export URL_GUESS_PATTERN
  ```

  Specifying URL\_GUESS\_PATTERN disables any guessing rules based on country.  An empty URL\_GUESS\_PATTERN disables any guessing that involves host name lookups.

## COPYRIGHT

Copyright 1997-1998, Gisle Aas

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.