Here is a tip for speeding up WordPress, especially if you are running it on a low power server. I made the change to WordPress running on a small ARM server, resulting in an immediate and dramatic speed up. It works because it prevents bots on the Internet from wasting your server resources. Continue reading
This article explains how to send email from the Raspberry Pi. It is a generic procedure and also works on other Debian distributions. This is not for receiving mail, only for sending it. (Receiving email on the Pi is a much more involved process, requiring your Pi to preform the role of a full mail server).
The ability to send mail across the internet is useful. It enables your scripts and applications to send you email about system events or sending data such as pictures from a webcam. Continue reading
This article discusses some of the caption and border effects available with the ImageMagick image processing package. ImageMagick is freely available for Linux and Windows. It offers a huge number of image processing options, so many in fact, that using the program can be a little tricky.
The following examples were evolved from the ImageMagick online documentation, plus a good deal of trial and error to get the details right. I used Linux, but the same commands should work under Windows. Continue reading
Solaris administrators may have seen the message “Catastrophic file error – zero length” in their system logs. Although it sounds serious, there is nothing “catastrophic” about it. This post explains how to stop the message from flooding your log files. Continue reading
This post shows how to use parallel processing to get a CPU intensive job done faster in Unix/Linux. By splitting a large task into several parts, it is quite easy to give each part to a separate CPU, and complete the task many times faster than it would on a single processor.
These days, even small PCs and other devices often come equipped with several CPU cores. But some tasks will use only one core, sometimes using 100% of it, while other cores stand by idle. Sometimes this is a waste of resources. Continue reading
There must be a few people out there who still use bc as a desk calculator. bc is a simple application that comes as standard on most unix and linux systems. It’s nicer to use than a graphical calculator app: less fussy, no mouse needed and you can see what you have typed.
bc Gets it Wrong
A recent mix-up with financial calculations lead me to discover that – unbelievably – bc was getting its sums wrong. This post explains the problem. Continue reading
Having problems logging into WordPress ? It’s a tricky area, with a seemingly endless list of problems, causes and recommendations. In my case, the “login” link would hang before even asking for a user name or password. The browser window would eventually give up saying “no response from server”. The blog was up and healthy, but logging in as admin (or any other user) was not possible. Continue reading
This is how to do a simple file system increase in Logical Volume Manager. For example, increasing /tmp from 512 Mb to 1 Gb.
/tmp is a logical volume:
# df -h /tmp Filesystem 1K-blocks Used Available Use% Mounted on /dev/mapper/vg00-tmpvol 496M 19M 452M 4% /tmp
Running “vgdisplay /dev/vg00” showed that volume group vg00 contained 3.5 Gb of free space. Extended the logical volume with lvextend: Continue reading
Running sshd in the foreground can be an effective way to debug ssh problems. In the following example, a user was unable to access a remote system using ssh keys. Running sshd in debug mode provided a quick resolution. Both source and target systems were Solaris, but the same method applies equally to Linux. Continue reading
Working on a client site recently, I noticed their Apache error log had grown to 32 Gb in size. The file was being written to at a rate of a quarter of a million lines a day, propelled by various cron jobs set up to run every 5 minutes. A PHP reconfiguration fixed the problem.
The box was a Solaris 10 system running “License Watcher“, and those messages was all coming from the License Watcher php code. Not genuine errors, just repeated diagnostics. I edited /usr/local/php/lib/php.ini and changed this line Continue reading