Fix to Try if WordPress Won’t Allow Comments

Posted on February 22, 2019 by curiouscat

One of the my blogs stopped allowing comments. If you experience this is might be due to an issue with https. The blog in question was serving https pages and everything had been working previously. I am not sure when the issue first appeared, but I noticed it after updating to WordPress v 5.1.

When I looked at the page source I could see the comment form was trying to submit to http (even though it was being submitted from a https page). I received a message that the page was going to be submitted in an insecure manner and did I want to submit anyway. I said yes and a new page was loaded (though it was blank). But no comment was submitted to the wordpress database.

Using another browser it gave a 405 error.

This page isn’t working
If the problem continues, contact the site owner.

HTTP ERROR 405

I couldn’t figure out why it was submitting to http. I remembered there is a general settings page (/wp-admin/options-general.php) and I went there and noticed the

WordPress Address (URL)
and
Site Address (URL)

fields were set to http. I updated them to https and then everything worked fine.

Copy Text From a File in Terminal

Posted on May 20, 2018 by curiouscat

If you just want to quickly copy the text of a file to the clipboard while in terminal you can just use:

cat [filename]

That will display the full text of the file to the terminal and you can just highlight the text and copy.

One case where this can be useful is as a quick and simple way to copy text to the clipboard of your laptop when you ssh into a remote server. If contents of the file are larger than a screen it can be difficult to scroll and copy the text you want to copy without using the cat command.

As a reminder: The intention for this site is quick and easy sample code and syntax reminders. I frequently forget the basic syntax of some thing I don’t use frequently and at times find it hard to find the simple basic information I want.

Fixing a Problem with WordPress Trackbacks and Pingbacks

Posted on April 29, 2018 by curiouscat

Trackbacks and pingbacks stopped working on several of my blogs. It turned out to be quite time consuming figuring out what was causing the problem. Eventually the following worked:

Installing php-xml

sudo apt-get install php-xml

And commenting out a check for empty $context variable (this doesn’t really make sense as the variable isn’t empty at this point but until it was commented out it just silently didn’t work) in the file wp-includes/class-wp-xmlrpc-server.php.

// if ( empty($context) ) // Link to target not found // return $this->pingback_error( 17, __( 'The source URL does not contain a link to the target URL, and so cannot be used as a source.' ) );

Anyway if the initial steps you take to deal when trackbacks and pingbacks on your blog stop working you might want to try these steps that worked for me.

Some Quick cli Syntax for Postgres

Posted on May 24, 2016 by curiouscat

How to Dump SQL result to a text file using cli

> psql -U postgres -d [database_name] -c ‘SELECT * FROM users’

How to exit postgres command-line utility psql
Type \q and then press ENTER to quit psql

Reset Root Password on MySQL Database
Notice that in PostgreSQL superuser is called postres (not root). If you forgot superuser password, you can reset it this way:

edit file pg_hba.conf

> sudo vim /etc/postgresql/9.3/main/pg_hba.conf

and find there a line similar to:

# TYPE  DATABASE        USER            ADDRESS                 METHOD
local   all             postgres                                md5

md5 here means that postgres asks for password. If there is this line then replace
md5 with peer, if there is no this line then add it

local   all             postgres                                peer

save the file, exit and reload postgresql service to pick up the updated configuration:

> sudo service postgresql reload

Then you should be able to get access to psql without providing a password this way:

> sudo -u postgres psql

In psql you can change user password using this command:

ALTER USER postgres PASSWORD 'new password';

PostgreSQL performance and monitoring

switch current database

\connect database_name or \c database_name

you can user autocomplete by pressing [tab]

list tables in current database

\dt

create a new database and import tables, data from a dump
in psql

CREATE DATABASE some_database

create a dump (in terminal)

> pg_dump dbname > outfile

You may notice that no password is used. That is because with Postgres you can setup a password file that is used to verify your access as such:

> vim ~/.pgpass

Then (format is hostname:port:database:username:password):

localhost:5432:mydbname:postgres:mypass
[ctrl-x] then confirm with y, then hit [enter]

save and exit

> chmod 600 ~/.pgpass

restore a dump (in terminal)

> psql dbname < infile

more details on dump-restore

create a user (it sql)

CREATE USER tester WITH PASSWORD 'test_password';
GRANT ALL PRIVILEGES ON DATABASE "test_database" to tester;

notice difference in quotation marks – in first case it must be single quotation mark ‘ and in the second case – double quotation mark “, otherwise PostgreSQL raises a syntax error

restart PostgreSQL

> sudo service postgresql restart

other regular service actions available too – [force-reload, reload, start, status, stop]

Also for Nginx (unrelated to this post really), Restart Nginx

sudo service nginx restart
other regular service actions available too – [force-reload, reload, start, status, stop]
reload only reloads configuration files, without stopping a service (which restart does)

How to Manually Run Cron Tasks

Posted on September 27, 2015 by curiouscat

To manually run cron tasks you can use the run-parts command in Linux.

So to run your cron-weekly, for example, to test that a fix you just made runs without error (this is what I just did, in fact)

run-parts /etc/cron-weekly

run-parts will run all the executables in a directory (you must point at the directory). So if you have several files in cron-weekly to run, you can’t just point to one of the files.

You may run into environmental differences running the script as a different user than the cron test runs at, so you can run as that user if needed. You need to be aware this is a quick and simple way of testing part of the process but it doesn’t do a perfect job of testing if it works as a cron task. But it will let you catch some failures quickly and fix them in time for the actual cron task to run. So do check that the everything works after the real cron job runs.

This is just the kind of thing I said I would put in this blog. Simple stuff but things I forget – so I put it here to remember and maybe help out others, like me, that need really basic tips.

If you have a cron task item (or have setup the whole task this way) that is just a script and you just want to test that 1 item you may run the script directly. For example (for a Linux shell script):

sh /etc/cron.weekly/your_crontask_script.sh

Chrome Remote Desktop

Posted on January 13, 2015 by curiouscat

I am more often frustrated by Google the last few years that pleased with them. But they do still provide some pretty awesome tools. For example, Chrome Remote Desktop lets you access a computer over the internet (and lets you to allow another user to access your computer securely over the internet).

Chrome Remote Desktop allows users to remotely access another computer through Chrome browser or a Chromebook. Computers can be made available on an short-term basis for scenarios such as ad hoc remote support, or on a more long-term basis for remote access to your applications and files.

screen shot of chrome remote desktop

Chrome Remote Desktop is fully cross-platform. Provide remote assistance to Windows, Mac and Linux users, or access your Windows (XP and above) and Mac (OS X 10.6 and above) desktops at any time, all from the Chrome browser on virtually any device, including Chromebooks (including Android phones and iPhones). The iPhone app is new.

Some users worry about installing such an app given all the spying and hacking scandals. That is not a completely crazy worry. Google, and others, have been taking advantage of weak user control (and even bugs and work arounds to avoid stated user preferences) to track users and use that information to make money selling ads. With many cool and useful tools there are risk of them being misused. And practices of governments and huge corporations have been so egregious to give a sensible person pause. Still in the right situations this is a pretty cool looking tool (similar things exist but the combination of price [this being free] and simplicity make this interesting).

Compare WordPress Files on Server to Proper WordPress Version

Posted on November 18, 2014 by curiouscat

Sadly one of the hassles in managing your own WordPress blog is dealing with people that use your blog to serve spam content. These hacks can insert spam links into your pages and posts or create spam directories that are completely their own content on your domain.

There are many issues to deal with in re-establishing control of your server; but that isn’t the scope of this post.

This is just a tips if you are troubleshooting to try and determine what is going on. Often your server has been hacked to allow uploaded php pages to be added or for WordPress php files to be edited.

One way to track down if the files have been changed or new ones added is to compare the WordPress files on your server to the current files for a fresh WordPress install. This assumes your blog is using the current version, which hopefully it is because on the big improvement WordPress made is to make those updates automatic. That greatly reduces the chance to have WordPress be the vector to infecting your server. If you were using a older version then just compare to the field for that version from the WordPress server.

If you don’t have a current backup I would make a backup before I tried this. Obviously, don’t make any deletions or changes to your server unless you understand what you are doing. You can create big problems for yourself.

You can use the diff command to view the difference between WordPress on your sever and the fresh install from WordPress. I install the new WordPress in a new directory outside public_html. At the cli on a Ubuntu/Linux server:

[code]sudo wget http://wordpress.org/wordpress-4.0.zip
unzip wordpress-4.0.zip
diff -rq wordpress ../public_html/[/code]

wordpress-4.0.zip – replace with whatever the version is you are using.
../public_html/blog/ – replace with the path to your blog

Continue reading →

Zoom Level on Embedded umap OpenStreetMaps

Posted on October 13, 2014 by curiouscat

Curious Cat uses OpenStreetMaps and umap to create my own maps. Then I can embed them on my sites, for example here for Chiang Mai Thailand.

For some reason when you use umap and select the embed option it gives you code that leaves off the zooming altogether. It is an easy fix (and I imagine the code will be fixed making this simple advice obsolete). But for now this is all you need to do.

The url umap adjusts as you zoom the map in your browswer. For example, going to

http://umap.openstreetmap.fr/en/map/chiang-mai_18602

which the Curious Cat Chiang Mai map it will “redirect” to some really far out zoom level

Then you can zoom in a bunch to get the level you want to use to embed.

http://umap.openstreetmap.fr/en/map/chiang-mai_18602#14/18.7851/98.9907

The code created for you to paste into your page is

[code]<iframe width="100%" height="300px" frameBorder="0" src="http://umap.openstreetmap.fr/en/map/chiang-mai_18602?scaleControl=false&miniMap=false&scrollWheelZoom=false&zoomControl=true&allowEdit=false&moreControl=true&datalayersControl=true&onLoadPanel=undefined"></iframe><p><a href="http://umap.openstreetmap.fr/en/map/chiang-mai_18602">See full screen</a></p>[/code]

Which doesn’t include any zooming info so you get the super far our zoom default.

You need to add to the url

[code]src="http://umap.openstreetmap.fr/en/map/chiang-mai_18602[/code]

so that it includes the zooming info. So it would be

[code]src="http://umap.openstreetmap.fr/en/map/chiang-mai_18602#14/18.7851/98.9907[/code]

You can also see the link to “See full screen” isn’t using the zoom settings. If you wanted that link to a zoom setting of your choice you can set that also.

Note the view on your screen and the embedded map isn’t going to be identical. The map will likely cut off some of what you see (due to the sizing of the embedded map). You can also adjust the sizing of the embedded map by adjusting the height (they default to 300px, but you can make it 400px or whatever you want).

How to Dump SQL Result to a Text File Using cli

Posted on September 15, 2014 by curiouscat

Just a quick tip on how to dump a sql result to a txt file.

mysql -e “select * from [table]” -u[user] -p [database] > sqlresult.txt

For example:

[bash]mysql -e "select * from orders where product_id = 15" -uroot -p > sqlresult.txt[/bash]

Turn It Off and On Again

Posted on May 8, 2014 by curiouscat

I had a WordPress blog lose the database connection. As I tried to troubleshoot it I rapidly got to the point of thinking that maybe just rebooting the server would fix things – since no changes had been made that should cause the database connection to be lost. But also I figured I couldn’t be so lucky that such a simple thing would work.

I tried to log into the database using the cli and it was failing. MySQL was still running – according to top. I have automated security updates setup for the VPS server running Ubuntu. My thought now is those updates somehow messed things up to the extent the server database connections somehow wasn’t working. I sure hoped that was the case.

I rebooted and hoped.

After a bit I was able to see that it was working.

When I went to reboot I noticed I hadn’t rebooted in a long time. My guess is I might have the automated security updates setup wrong on this server (maybe it is installing more than just the security updates), I’ll check. I have not had this problem before with other servers, obviously breaking a database in this way would cause lots of problems on production machines so I tend to think it is more likely I messed something up than this is a likely outcome when using automated security updates (but such things are possible which is why I think places with full time system admins and important servers rely on manual updates with professionals watching everything to be sure nothing obvious breaks).

My feeling is the longer you go with not rebooting the server the more likely some issues are to crop up (but also every reboot is more like to result in some broken thing, right then, than doing nothing so it is a tradeoff). And I could be wrong in that feeling, it is just what I guess without much evidence to support my guess.

Anyway I was very happy turning it off and on again worked. Honestly I went ahead and updated the server before I rebooted, but my guess is just turning it off and on again would have worked.

Curious Cat Code

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