Validate External Links: Difference between revisions

From OniGalore
Jump to navigation Jump to search
(→‎How to fix bad links: improving documentation, linking to new reference subpages)
m (link fix)
 
(14 intermediate revisions by 2 users not shown)
Line 1: Line 1:
Developed by [[User:Iritscen|Iritscen]], Validate External Links ("ValExtLinks" for short, or "Val" for even shorter) is a script made to help fight the battle against [[wikt:linkrot|link rot]] on OniGalore.
Developed by [[User:Iritscen|Iritscen]], Validate External Links ("ValExtLinks" for short, or "Val" for even shorter) is a Bash shell script made to help fight the battle against [[wikt:linkrot|link rot]] on OniGalore. The latest report on link issues is found '''[http://iritscen.oni2.net/val/ValExtLinks%20report.htm HERE]'''. Further link work which requires a bot is performed by [[User:ValBot|ValBot]].


==Background==
==Background==
While MediaWiki makes it easy to find bad links to pages on our own wiki, marking them in red and providing tools like [[Special:Wantedpages|Wantedpages]], there is no automatic check of external links. MediaWiki compiles external links into a table, but it does not ping the URLs to see if they give any response. The most you are allowed to do is [[Special:LinkSearch|search]] through the links table, and even that isn't implemented well. Over the years, many links on our wiki have gone dead as the Web has changed and various file hosts have gone out of business.
While MediaWiki makes it easy to find bad intrawiki links (links to nonexistent pages on our own wiki) by marking them in red and providing tools like [[Special:Wantedpages]], there is no automatic check of external (outbound) links. MediaWiki compiles external links into a table, but it does not ping the URLs to see if they give any response. Over the years, many links on our wiki went dead as the Web changed and various file hosts went out of business. ValExtLinks has been used to fix thousands of link issues on OniGalore such as 404s and redirects.


So here's how ValExtLinks helps with this: at 6:20am and 2:20pm (GMT) each day, a script written by [[User:Admin|Alloc]] dumps the wiki's external links table to [http://wiki.oni2.net/w/extlinks.csv this location]. Val, which runs on Iritscen's computer at 3:00pm (GMT) each day, then walks through the table and looks for URLs that return problematic codes such as 404. It also detects other lesser problems with links. Val then makes suggestions for fixing these links.
Here's how the process works: twice a day (6:20am and 2:20pm GMT), a script written by [[User:Admin|Alloc]] dumps the wiki's external links table to [https://wiki.oni2.net/w/extlinks.csv this location]. ValExtLinks, which Iritscen runs on his computer periodically, walks through the exported table and looks for URLs that return problematic responses such as 301 and 404. It also detects other lesser problems with links. Val then makes suggestions for fixing these links and uploads its findings in HTML, RTF and TXT formats to [http://iritscen.oni2.net/val/ this directory]. Any wiki editor can then review the reports and act accordingly.


==How to fix link issues==
==Running and contributing==
*'''NG''': In most cases, fixing an [[wp:List_of_Japanese_Latin_alphabetic_abbreviations#N|"NG"]] link will mean finding the desired web page in the Internet Archive's [https://archive.org/web/ Wayback Machine] and linking to that archived page instead. In some cases, an NG link will not be recoverable and should be either removed from the page or, if the link was a part of a conversation and it would be confusing for it to be absent, it should be surrounded in nowiki tags [[Special:Diff/16377/26212|like this]] to prevent it from showing up in future reports.
The project is found [https://websvn.illy.bz/listing.php?repname=Oni2&path=%2FValidate+External+Links%2F HERE]. Along with the Bash shell script itself, you'll find documentation on how to run ValExtLinks on your own computer as well as resources for contributing to the code.
**Val automatically queries the Archive for the latest snapshot of each NG page and will put the returned snapshot URL in its report. Note that you still have to verify this link by clicking on it, as it may not have the correct content. You may have to go further back in the Wayback Machine to find the proper snapshot to use. Sometimes the Archive simply never got around to archiving a given site. In that case, you will need to follow the advice above as to deleting the link or marking it with nowiki tags.
 
*'''RD''': The site is redirecting the browser to a new page. The new page should be evaluated, and if it has the content we intended to link to then we should update the link to point to the new location. However, many redirects actually are "soft 404s" and simply redirect the browser to the site's main page. In this case, an RD link needs to be treated like an NG link (see above).
==Fixing link issues in a report==
*'''EI''': An external link (bare URL) for a page on our own wiki that could simply be an [[Help:Editing#Intrawiki_links|intrawiki link]]. Sometimes an "external internal" may seem to be necessary, but there's a special wiki feature that allows you to avoid it:
Here are the codes that you'll see applied to problem links in the report.
**If you want to link to a specific version of a page, which used to require putting the full URL, [http://wiki.oni2.net/w/index.php?title=Oni&oldid=7685 like this]. In fact, there's no need to link to any page at all, as the "ID" of an edit, like the one you see in that sample URL, is unique wiki-wide. All you need to do is supply the revision ID to the Special:Permalink page like this — [[Special:Permalink/7685]] — and you're done.
*'''NG''': In most cases, fixing an NG ("no good") link will mean finding the desired web page in the Internet Archive's [https://web.archive.org/ Wayback Machine] and linking to that archived copy instead. In some cases, an NG link will not be salvageable and should be either removed from the page or, if the link was a part of a conversation and it would be confusing for it to be absent, it should be surrounded in <code>nowiki</code> tags [[Special:Diff/40524|like this]] to prevent it from showing up in future reports.
**If you need to link to a diff between two revisions of a page, or between two different pages, plug the old and new revision numbers into the Special:Diff page like this: [[Special:Diff/21491/21492]] (no need for page names, as explained above).
**Val automatically queries the Archive for the latest snapshot of each NG page and will put this snapshot URL in its report. Note that you should still check this snapshot to make sure it has the desired content. You may have to go further back in the Wayback Machine to find the proper snapshot to use. Sometimes the Archive simply never got around to archiving a given site. In that case, you will need to follow the advice above as to deleting the link or marking it with <code>nowiki</code> tags.
**If there's no provision like this for replacing a bare URL with a smarter link, see "Exceptions" below to remove the link from the report.
**Note: In a typical run of ValExtLinks across the 3,500 links on the wiki, 1-3 sites will happen to be offline at the moment or the HTTP packets requesting them will get lost in cyberspace. Before attempting to perform any of the above fixes, try the link manually to make sure the site is really down. Even if it is, you might want to wait for next week's Val report to see if the site is permanently dead.
*'''IW''': An external link (bare URL) that could be an [[Help:Editing#Interwiki_links|interwiki link]]. Interwiki links are shorter and more resistant to rot. The suggested interwiki link markup will be given in the report. For foreign-language Wikipedia pages, you can add a language code, e.g. <nowiki>[[wp:de:Test]]</nowiki> for the German version of the page.
*'''RD''': The site is redirecting the browser to a new page. If the new page has the content we intended to link to, we should update the link to point to this new location. Be aware that some redirects are actually "soft 404s", redirecting the browser to the site's main page. In this case, an RD link needs to be treated like an NG link (see above).
*'''(xxx)''': The HTTP response code (see reference [[/HTTP codes|HERE]]).
*'''EI''': An "external internal" link, that is, a full URL for a page that is on our own wiki and which should simply be an [[Help:Editing#Intrawiki links|intrawiki link]]. Sometimes an "external internal" may seem to be necessary but can be avoided with one of these special wiki features:
*'''(000-xx)''': The Unix tool 'curl' did not get an HTTP response code, but instead returned this exit code (see [[/Curl codes|HERE]]). The most common by far is "000-28", a timeout.
**If you want to link to a specific revision of a page, you might think you need a full URL [https://wiki.oni2.net/w/index.php?title=Oni&oldid=7685 like this one]. There's actually no need to link to any page at all, as the "ID" of a page revision (which you will see in that sample URL) is unique wiki-wide. All you need to do is supply the revision ID to the Special:Permalink page like this — [[Special:Permalink/7685]] — and you're done.
**If you want to link to a specific revision as a diff from the previous revision of that page, plug the revision number into the Special:Diff page like this: [[Special:Diff/40550]] (no need for page names, as explained above). To link to a diff between two non-contiguous revisions of a page or between two different pages, plug the old and new revision numbers into the Special:Diff page like this: [[Special:Diff/21491/21492]].
**If there's no way around a bare URL, see the "Exceptions" section below to learn how to remove the link from the report.
*'''IW''': This marks an external link (bare URL) to another wiki which could be an [[Help:Editing#Interwiki links|interwiki link]]. Interwiki links are shorter and more resistant to rot. The suggested interwiki link markup will be given in the report. For foreign-language Wikipedia pages, you can add a language code, e.g. <nowiki>[[wp:de:Test]]</nowiki> for the German version of the page "Test".
*'''(xxx)''': The HTTP response code (see HTTP code reference [[/HTTP codes|HERE]]).
*'''(000-xx)''': The exit code from the Unix tool 'curl', for cases where it failed to get an HTTP response code (see 'curl' code reference [[/Curl codes|HERE]]). The most common 'curl' error by far is "000-28", a timeout from an unresponsive site.


===Exceptions===
===Exceptions===
Some links simply have to be presented the way that they are. Some links return error codes but actually work fine. These links can be added to the [[/Exceptions|exceptions list]] in order to hide them in future reports.
Some links simply must be presented in an unconventional way which Val thinks is a problem. Some links return error codes but actually work fine. Such links can be added to the [[/Exceptions|exceptions list]] in order to hide them in future reports.
 
==Coming features==
*It seems that many external links no longer display the content that they were intended to display. In many cases, web sites are silently redirecting the user to their main page without using the appropriate code that indicates the content was not found. Only visual inspections of the pages can catch these issues. Once we have dealt with the low-hanging fruit of pages that return "NG" codes, the screenshot feature in the script will be activated, which will allow us to easily confirm if the "OK" links (and snapshots from the Internet Archive) are actually loading the intended page.
 
*Over time, the exceptions list should be audited so it doesn't acquire [[wikt:cruft|cruft]]. Val needs to mention URLs in the list that aren't in extlinks.csv anymore, and URLs which returned different codes from what was expected.
 
*Val will eventually expand and test the interwiki links. Currently there is no way to know if they've gone bad.
 
*Test section links found in interwiki and intrawiki links. Even intrawiki links will only show up as redlinks if the page itself does not exist; MediaWiki does not look at the section anchor to see if it exists.
 
*If possible, Val will eventually start warning about externally-hosted images, as many of these have gone down with their file hosts over the years.


==Source code==
In the summary at the bottom of a ValExtLinks report, Val will list any exception that didn't have the intended effect because the link is no longer present on the listed page or because it doesn't return the expected error code anymore. You can then edit the wiki's exceptions list accordingly. Note that the HTML report only gives the number of exception issues detected, and the actual list of issues is found in the RTF and TXT versions of the report.
The Bash script and related files are found [http://websvn.chrilly.net/listing.php?repname=Oni2&path=%2FValidate+External+Links%2F here].


[[Category:Wiki Support]]
[[Category:Wiki Support]]

Latest revision as of 14:42, 24 March 2024

Developed by Iritscen, Validate External Links ("ValExtLinks" for short, or "Val" for even shorter) is a Bash shell script made to help fight the battle against link rot on OniGalore. The latest report on link issues is found HERE. Further link work which requires a bot is performed by ValBot.

Background

While MediaWiki makes it easy to find bad intrawiki links (links to nonexistent pages on our own wiki) by marking them in red and providing tools like Special:Wantedpages, there is no automatic check of external (outbound) links. MediaWiki compiles external links into a table, but it does not ping the URLs to see if they give any response. Over the years, many links on our wiki went dead as the Web changed and various file hosts went out of business. ValExtLinks has been used to fix thousands of link issues on OniGalore such as 404s and redirects.

Here's how the process works: twice a day (6:20am and 2:20pm GMT), a script written by Alloc dumps the wiki's external links table to this location. ValExtLinks, which Iritscen runs on his computer periodically, walks through the exported table and looks for URLs that return problematic responses such as 301 and 404. It also detects other lesser problems with links. Val then makes suggestions for fixing these links and uploads its findings in HTML, RTF and TXT formats to this directory. Any wiki editor can then review the reports and act accordingly.

Running and contributing

The project is found HERE. Along with the Bash shell script itself, you'll find documentation on how to run ValExtLinks on your own computer as well as resources for contributing to the code.

Fixing link issues in a report

Here are the codes that you'll see applied to problem links in the report.

  • NG: In most cases, fixing an NG ("no good") link will mean finding the desired web page in the Internet Archive's Wayback Machine and linking to that archived copy instead. In some cases, an NG link will not be salvageable and should be either removed from the page or, if the link was a part of a conversation and it would be confusing for it to be absent, it should be surrounded in nowiki tags like this to prevent it from showing up in future reports.
    • Val automatically queries the Archive for the latest snapshot of each NG page and will put this snapshot URL in its report. Note that you should still check this snapshot to make sure it has the desired content. You may have to go further back in the Wayback Machine to find the proper snapshot to use. Sometimes the Archive simply never got around to archiving a given site. In that case, you will need to follow the advice above as to deleting the link or marking it with nowiki tags.
    • Note: In a typical run of ValExtLinks across the 3,500 links on the wiki, 1-3 sites will happen to be offline at the moment or the HTTP packets requesting them will get lost in cyberspace. Before attempting to perform any of the above fixes, try the link manually to make sure the site is really down. Even if it is, you might want to wait for next week's Val report to see if the site is permanently dead.
  • RD: The site is redirecting the browser to a new page. If the new page has the content we intended to link to, we should update the link to point to this new location. Be aware that some redirects are actually "soft 404s", redirecting the browser to the site's main page. In this case, an RD link needs to be treated like an NG link (see above).
  • EI: An "external internal" link, that is, a full URL for a page that is on our own wiki and which should simply be an intrawiki link. Sometimes an "external internal" may seem to be necessary but can be avoided with one of these special wiki features:
    • If you want to link to a specific revision of a page, you might think you need a full URL like this one. There's actually no need to link to any page at all, as the "ID" of a page revision (which you will see in that sample URL) is unique wiki-wide. All you need to do is supply the revision ID to the Special:Permalink page like this — Special:Permalink/7685 — and you're done.
    • If you want to link to a specific revision as a diff from the previous revision of that page, plug the revision number into the Special:Diff page like this: Special:Diff/40550 (no need for page names, as explained above). To link to a diff between two non-contiguous revisions of a page or between two different pages, plug the old and new revision numbers into the Special:Diff page like this: Special:Diff/21491/21492.
    • If there's no way around a bare URL, see the "Exceptions" section below to learn how to remove the link from the report.
  • IW: This marks an external link (bare URL) to another wiki which could be an interwiki link. Interwiki links are shorter and more resistant to rot. The suggested interwiki link markup will be given in the report. For foreign-language Wikipedia pages, you can add a language code, e.g. [[wp:de:Test]] for the German version of the page "Test".
  • (xxx): The HTTP response code (see HTTP code reference HERE).
  • (000-xx): The exit code from the Unix tool 'curl', for cases where it failed to get an HTTP response code (see 'curl' code reference HERE). The most common 'curl' error by far is "000-28", a timeout from an unresponsive site.

Exceptions

Some links simply must be presented in an unconventional way which Val thinks is a problem. Some links return error codes but actually work fine. Such links can be added to the exceptions list in order to hide them in future reports.

In the summary at the bottom of a ValExtLinks report, Val will list any exception that didn't have the intended effect because the link is no longer present on the listed page or because it doesn't return the expected error code anymore. You can then edit the wiki's exceptions list accordingly. Note that the HTML report only gives the number of exception issues detected, and the actual list of issues is found in the RTF and TXT versions of the report.