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

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 →

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]

Reset Root Password on MySQL Database

Posted on August 15, 2014 by curiouscat

How to reset the root password on a MySQL database.

Stop mysql using this command:

[bash]sudo /etc/init.d/mysql stop[/bash]

Because you are not checking user privledges at this point, it’s safest to disable networking. Then, start the mysqld demon process using the –skip-grant-tables option using

[bash]sudo /usr/sbin/mysqld –skip-grant-tables –skip-networking &[/bash]

Next, start the mysql client process using this command:

[bash]mysql -u root[/bash]

from the mysql prompt execute this command to be able to change any password

[bash]FLUSH PRIVILEGES;[/bash]

Then reset/update your password

[bash]SET PASSWORD FOR root@’localhost’ = PASSWORD(‘password’);[/bash]

Make Your Bounce Rate More Meaningful

Posted on May 26, 2013 by curiouscat

Nice post on what the operational definition (though it doesn’t use that term) of bounce rate is in Google Analytics and some ideas on how to fix bounce rate to be more meaningful (better fit your desired operational definition).

We often make mistakes because we use the data we have assuming it means something other than what it actually means. There suggestions let you make Google Analytics collect the data so it is more aligned to what you want to know.

Essentially bounce rate without any adjustment is operationally defined by Google to mean the visitor doesn’t click a link to another page on your site that has Google Analytic code (so it can register the click).

They suggested using

[javascript]setTimeout("_gaq.push([‘_trackEvent’, ’15_seconds’, ‘read’])", 15000);[/javascript]

inside your Google analytic tracking code. They also updated the post with an idea from a Hacker News comment to use scroll tracking as a better option than just timing if they stay on the page at least 15 seconds. The scroll tracking lets you count it as a bounce only if they don’t scroll down and they don’t click to a new page on your site.

Which data is more useful depends on your situation, what you want to know and what you want to do with the data you collect.

Don’t Copy-Paste Directly from Website to Terminal

Posted on April 8, 2013 by curiouscat

Good reminder and discussion on Hacker News about the danger of copy-paste from a website into terminal.

When copying from a website it is easy for hidden text to be included in the clipboard. If you paste that into terminal it can be executed before you see the code. Including new line commands in the copied text will automatically execute the commands (in most terminal applications).

The best solution is to paste the clipboard content into something to view the text before pasting into clipboard. The best way is probably to recopy it. I use this double copy method to get rid of formatting I don’t want (when the clipboard includes things like font styling info you don’t want – not relavent when pasting into terminal but the pasting [into say vim, which won’t include the extra formatting details] and recopying part is similar). It may be possible to have text hidden (write it in a way where it won’t show up on the screen but is in the clipboard – using some tricky unicode characters or something).

Some people put # before pasting into clipboard but that only protects the first “line.” Any new lines could still be run without you seeing them.

The discussion warns against a malicious website intentionally creating a problem but if you paste in multiple lines there is also just the danger from the lines executing immediately when you wanted to edit the line before it was executed.

Making Sure You Don’t Run Out of Space on Your VPS

Posted on February 6, 2013 by curiouscat

Over the years I have had web sites I work on go down because the server ran out of space (when I wasn’t responsible for the system administration). Well today I had it happen for some sites on one of my servers.

I have a remote monitoring service so I was notified when the sites were unavailable. Looking in the error logs I could see I ran out of space, which is a fairly lame error to make, I think. I cleared up some space quickly and things were in working order again.

A few tips from this experience. To see data on space used and available space from the command line (linux/ubuntu) use the df command.

[bash]df[/bash]

You could check that occasionally to see if anything strange is going on. But it is better to use something like Nagios to monitor the server and provide notice if usage goes past certain points is wise (75%, 80%…).

I found a nice way to find large files (that may be possible to delete to free up space)

[bash]sudo find . -mount -ls | awk ‘{print $7, $11}’ | sort -rn > large_file_list[/bash]

If you get an error with the file creation, you can log in as root (su) or create the file first and then it can overwrite the existing file.

It is smart to have log rotate setup for logs. I didn’t have it setup for every log. To create a file to keep track of all your logs for domains you can do the following. Create a file in the logrotate directory so it is run per your settings.

[bash]sudo vim /etc/logrotate.d/virtualhosts[/bash]

This article from Slicehost provide details on options, a simple setup is to include text such as this in the file created in the line above.

[bash]/var/www/domain1.com/logs/*log /var/www/domain2.com/logs/*log {
rotate 14
daily
compress
delaycompress
sharedscripts
postrotate
/usr/sbin/apache2ctl graceful > /dev/null
endscript
}[/bash]

Continue reading →

ModSecurity – Adjustments for WordPress

Posted on January 6, 2013 by curiouscat

How to secure an Ubuntu 12.04 LTS server – Part 1 The Basics is a great resource to secure a VPS.

Mod_Security is a web application firewall. I found a couple things to add to my servers.

The same site includes a very good guide to installing it (you also may well want to whitelist Googlebot, instructions in the link). However it blocked my access to one of my sites. You end up just getting the message:

“Forbidden

You don’t have permission to access / on this server.”

There are tips on some edits to include when using WordPress on an Apache server with modsecurity.

One simple action is to include

SecRule SERVER_NAME “[your-domain.com]” phase:1,nolog,allow,ctl:ruleEngine=off

[bash]SecRule SERVER_NAME "code.curiouscatnetwork.com" phase:1,nolog,allow,ctl:ruleEngine=off[/bash]

on the bottom of modsecurity.conf which is found /etc/modsecurity (for me, on Ubunutu 12.04). Then restart Apache

[bash]sudo service apache2 restart[/bash]

and see if the problem goes away. If it does then you have a very good indication modsecurity was blocking access and can continue to narrow the scope of the problem by adding the WordPress whitelist rules in the link above.

Another note, service apache2 start, failed in a non-obvious way to me anyway. For me if I use sudo it works fine. If I don’t it gives odd errors which lead me on a 10 minute wild goose chase before remembering to try sudo.

Set the Web Server to Use the Domain Without www

Posted on April 26, 2012 by curiouscat

The main reason to bother with this is to help search rankings. Sub-domains (for example, www.curiouscat.com and curiouscat.com) are treated as separate websites even if you have entirely the same content displayed for both. If 20% of the links to your site use the www and 80% don’t then your sites ranking by search engines is less than it would be if it was just treated as one site.

You can set the domain to use in Google webmaster tools. But that doesn’t do anything for all the other search engines. Also if you have both, some reports some will keep statistics separately for the non-www and www domain (Google Adsense does this, for example).

Using virtual hosts file (sites-enabled)

For Apache you can place the following code in your virtual hosts file (in the sites-available directory under Apache).

Replace curiouscat.com with your domain name.

[bash]<Directory /srv/www/curiouscat.com/public_html/>
RewriteEngine On
RewriteCond %{HTTP_HOST} ^www.curiouscat.com$ [NC]
RewriteRule ^(.*)$ http://curiouscat.com/$1 [R=301,L]
</Directory>[/bash]

Then you need to capture the update and reload Apache.

Disable the site (in order to enable it with the updates)
[bash]sudo a2dissite curiouscat.com[/bash]
Enable the site
[bash]sudo a2ensite curiouscat.com[/bash]
Reload Apache (new way – Ubuntu 12.04)
[bash]sudo service apache2 reload[/bash]
Old way to reload Apache was > sudo /etc/init.d/apache2 reload

If when you try to reload you get this error message:

“Invalid command ‘RewriteEngine’, perhaps misspelled or defined by a module not included in the server configuration” then enable modrewrite on apache:

[bash]sudo a2enmod rewrite[/bash]

You should then be told to restart apache

[bash]sudo /etc/init.d/apache2 restart[/bash]

Using .htaccess

Or you can include the following in your .htaccess file

[bash] RewriteEngine On
RewriteCond %{HTTP_HOST} ^www.curiouscat.com$ [NC]
RewriteRule ^(.*)$ http://curiouscat.com/$1 [R=301,L][/bash]

If you wanted to force www to be used instead just flip the regular expression around:

[bash]<Directory /srv/www/curiouscat.com/public_html/>
RewriteEngine On
RewriteCond %{HTTP_HOST} ^curiouscat.com$ [NC]
RewriteRule ^(.*)$ http://www.curiouscat.com/$1 [R=301,L]
</Directory>[/bash]

Replace Text in Files Recursively (Linux)

Posted on February 20, 2011 by curiouscat

To replace text in all the files in a directory, recursively, you can use grep.

sudo grep -rl texttoreplace /somedirectory/ | sudo xargs sed -i ‘s/repacethis/withthis/g’

[bash]sudo grep -rl oldtext /example/directory/ | sudo xargs sed -i ‘s/oldtext/newtext/g'[/bash]

The g on the end, lets it replace all the instances of the text in each file.

More ubuntu and linux tips and code samples

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