Extension:Replace Text

Replace Text is an extension to MediaWiki that provides a special page, as well as a command-line script, to allow administrators to do a server-side global string find-and-replace on both the text and titles of the wiki's content pages.

The replace text operation is a deferred operation and posted to the job queue. You can run from the  folder to perform the replacement immediately and process the job queue.

Usage
Replace Text defines a special page, at " Special:ReplaceText " (or its equivalent in another language), that handles global searching and replacing; it also defines a script, replaceAll.php, that does the same thing from the command line. This documentation will cover the special page first, then the command-line script.

The page Special:ReplaceText initially displays a form for an administrator to fill out the search-and-replace details: the administrator enters a search string and its replacement, the set of namespaces on which to search, as well as choosing whether to replace text within page contents, page titles, or both. Optionally, the administrator can also add two additional filters: the name of a category that all pages must belong to, and a prefix that all page names must start with. When this form is submitted, they are then shown a list of either all the pages that contain that search string, or all the pages whose titles contain the search string, or both. Next to each page name is a checkbox for each, so that they can unselect whichever pages they don't want replaced. The user then can hit "Replace" to do the actual replacement. Once a text replace is done, it is not directly undoable; though you can always run a "reverse" replace, replacing the new string with the original string. For that reason, if the replacement string is blank or is a string that already exists in the wiki, the user is shown a warning message.

If the search string is contained multiple times on a page, every such instance is replaced. Every page's replacements shows up as a (minor) wiki edit, with the administrator who performed the text replacement as the user who made the edit and an edit summary that looks like "Text replace: ' search string ' to ' replacement string '".

A page's title cannot be moved to a title that already exists in the wiki, or to a title that is multiple lines. Pages that cannot be moved will be simply listed on the "select" page as being unmovable, without a checkbox near them.

The search is case-sensitive. See below for how to make it case-insensitive.

Things to know

 * 1) ReplaceText only processes 250 pages at a time by default.  To change this, you can set  to a larger value in your LocalSettings.php.  However, you may be limited by PHP's  ; if the extension reports such a warning, you may need to change it.
 * 2) All of the replacements are placed in the job queue.  So if you have to process a large number of pages, you will need to run Replace Text and then run "  " (potentially multiple times).

Using regular expressions
If you are using a MySQL or PostgreSQL database, you will see a "Use regular expressions" checkbox within the Special:ReplaceText form. This checkbox does not appear for SQLite databases, because SQLite lacks a native " REGEXP " operator.

If you click on this checkbox, you can use regular expressions, or regexps, within the search and replacement strings. The set of regular expressions allowed is basically a small subset of the PHP and MySQL/PostgreSQL regular-expression set. The special characters that one can use in the search string are " . * + ? [ ] | ", and within the replacement string one can use values like $1, $2 etc. (To use these as regular characters, you just need to escape them by adding a " \ " beforehand - which you would also need to do with the " / " character.) This section will not give a tutorial on using regular expressions (the Wikipedia article is a good place to start for that, as is [ http://dev.mysql.com/doc/refman/5.1/en/regexp.html#operator_regexp this page on MySQL regexps]), but here is the basic example listed in the inline explanation:


 * Search string -
 * Replacement string -

This would look for pages containing the letter 'a', the letter 'c', and any text in between (signified by the " .* "). It would then put that middle text after the 'a' and 'c' - the "$1" in the replacement string refers to the first element of the search string contained within parentheses (in this case, there's only one).

For every page for which the replace is actually called, the replacement would happen for every occurrence of the search string, not just one - just as happens with regular, non-regular-expression search.

More complex regexps

 * Search string -
 * Replacement string -

This would replace " hello222.555 " with " 222,555 " and " hello2.55" with "2,55 "

First the word " hello " is matched. In brackets follows an expression to search for any digits " 0-9 ". The following asterisk finds multiple matches of the preceding element. The brackets and the asterisk get enclosed with parantheses, so we match the complete term and transfer it to $1. The " \. " indicates that it's a true dot, and not a special character. The second expression within parentheses is matched and put into $2.

Replacements followed by numbers
The following will not work:


 * Search string -
 * Replacement string -

That's because the search will think the number of the replacement is 1123456, not 1. Instead, you should have the following:


 * Replacement string -

In general, you can always enclose numbered values in curly brackets.

Case-insensitive search
To make your search case-insensitive, use regular expression and the case-insensitive modifier, :
 * Search string:
 * Replacement string:

The above will unify the casing of all mentions of iPhone/iphone/IPHONE to iPhone.

Command-line script: replaceAll.php
Replace Text offers a script, replaceAll.php, in the  directory, which can be run from the command line, and which does all the same replacements that the page Special:ReplaceText does. The first two arguments for this script should be the search text and the replacement text; you can call this script simply like the following: php replaceAll.php "Leningrad" "St. Petersburg"

If you use numbered values like $1 in the replacement string, you have to either escape them inside double quotes like  or use single quotes. Otherwise the shell will put blanks in their place as it thinks they are variables.

Other possible arguments/flags for this script are:
 * - only find the search texts, without doing any actual replacements
 * - regular expressions should be used (default is false)
 * - the user to attribute the replacements to (default is the user with ID 1)
 * - skip all prompts with an assumed "yes"
 * - set a custom edit summary for the replacement edits
 * - rename page titles instead of replacing contents
 * - do not announce edits on Special:RecentChanges or watchlists
 * - set a comma-separated list of the namespaces to search
 * - search on all the namespaces; overrides any value set for "--ns"
 * - the name of a file holding a tab-separated list of replacements to make
 * - display the replacements being made

Additionally, there are two flags that strictly print out helpful information unrelated to a specific text replacement:
 * - show a description of the file format to use with
 * - show a list of all namespaces on this wiki

(You can also see all of these options by calling "php replaceAll.php --help".)

Assigning replacements to a user
By default, all replacements are credited in the page history to the user who initiated them. However, you can instead have replacements be credited to a pre-set user -- such as a bot account -- by adding a line like this to LocalSettings.php, below the inclusion of Replace Text:

The username specified must already be an account on the wiki. It will be added to MediaWiki's array of usernames which may not be registered or logged in from.

Authors
Replace Text was mostly written by Yaron Koren, reachable at yaron57@undefinedgmail.com. Important contributions were also made by Niklas Laxström, Ankit Garg (who contributed much of the regular expression code), Mark Hershberger (who wrote the command-line script), Brent Laabs, Cindy Cicalese, Nikhil Kumar, Umherirrender, James Forrester, Fomafix, Marijn van Wezel, Sahaj Khandelwal and others.

Version history
Replace Text is currently at version 1.7. See the entire version history.

Screenshots
Below are images of the workflow of Replace Text. First, the initial page in which "George F. Will" and "George Will" are entered for the target string and replacement string, respectively, and replacing text in page titles is specified as well, on Discourse DB:



Note: the check "All" and "None" boxes only show up when using the Vector skin, or skins based off of it.

And here is what the page looks like after the user hits "Continue":



Hitting "Replace" would replace this value in all of the listed pages, as well as moving the page at the end to its new value.

Known issues

 * The replacement actions themselves are structured as MediaWiki "jobs", to ensure that the system is not overloaded if the user wants to do many at the same time. This means that a large set of replacements will not be done immediately, and may take minutes, hours or even longer to complete. Normally, jobs get activated every time a page is viewed on the wiki; to speed up the process (or slow it down), you can change the number of jobs run when a page is viewed; the default is 1. Thus a Replace Text request can stall soon after it starts if there is not enough front-end activity on the wiki to outrun the other sources of new batch jobs. For information on how to change the default, see the  page. To force the wiki to run all jobs immediately, go to the shell and execute the script ; there generally isn't a way to do this from the wiki's front end.
 * For getting the jobs to run on a seldom-used wiki, for instance a working wiki for a small hobby project team, you can for instance force a refresh of the "All pages" special page. This can be done for instance by using the following shell script on Unix:
 * If you are still having a problem with getting Replace Text's jobs to run, adding the following to LocalSettings.php may fix the problem:
 * If you are still having a problem with getting Replace Text's jobs to run, adding the following to LocalSettings.php may fix the problem:


 * In order for redirects not to be created on page moves (i.e. if the "Save the old titles as redirects to the new titles" checkbox is unchecked), you will have to give the relevant user the 'suppressredirect' permission. Assuming you've given the 'replacetext' permission to a "trusted-editor" user group, you would need to add the following to LocalSettings.php:


 * If your revisions are compressed (that is, if is enabled in  or the script  has been executed with the option  ) then ReplaceText will not work, because it makes use of SQL queries that can't search compressed text. (see the MassEditRegex extension as an alternative in this case.)
 * If you have a large number of replacements, some of them may not get done; or you may see an error message that reads "You must select at least one namespace." In both cases, that's due to a limit on the number of form inputs that PHP accepts. This can be fixed in a number of ways:
 * If you have the Suhosin PHP extension installed on your server, that may be source of the problem. You can increase the value of the variables  and  ; or simply try temporarily disabling Suhosin while you do the replacements.
 * The PHP setting  (available since PHP 5.3.9) also affects the number of replacements you can do at any time - you can try setting this to a very large number, like 3000.

Translating
Translation of Replace Text is done through translatewiki.net. The translation for this extension can be found here. To add language values or change existing ones, you should create an account on translatewiki.net, then request permission from the administrators to translate a certain language or languages on this page (this is a very simple process). Once you have permission for a given language, you can log in and add or edit whatever messages you want to in that language.