How to fix intermittent failure of multiple Dropboxes on Ubuntu


I noticed an off-and-on problem with a Linux server running two Dropbox daemons to update two different folders containing synchronized files from two Dropbox accounts. Often, at log-in, one or more Taskbar Dropbox icons would signal that its process was endlessly trying-and-failing to sync.

Sometimes, I could fix this by stopping and restarting one or other of the instances; but I didn’t think too deeply about why or what was the cause. It turns out that it was conflicting versions of the Dropbox daemon running simultaneously and/or one of those versions needing to be updated.

The fix that I link to here (which is by Realflash) is possibly not a permanent one—because, after you delete the conflicting executables, unless they are right up-to-date, Dropbox restores them—but it will probably persist for longer than my crude turn-it-off-and-on-again kludge.


PHP Programming: Warning: PHP Arrays are undefined or uncleared until you reset them.

Beware! This is a subtle problem that can have serious consequences for the operation of your PHP code. If you do not explicitly assign at least one value to a new array (or an array that you are going to use anew in loop, say) or set it to be empty, then it will either have undefined contents (or it will contain values that were previously assigned to it in a previous loop).

If you have any doubt that you are immediately going to assign defined values to the array (or even if you don’t), you must specifically clear the array like this:

$my_undefined_array = array();

Review: MPOW USB Skype Headset

MPOW USB Skype headset

This is cheap and does its job well. So well that I bought a second one, after months of good service from my first, so I could have one in my office-office and one in my home office. It’s currently available, in a small range of colours, for under £20 on Amazon.

I’m not a gamer and I wouldn’t call its sound “hi-fi”, but this is an excellent-value headset for all the forms of duplex computer communication I’ve used it with: Skype (which it’s promoted as being suitable for), Google Hangouts, and GoToMeeting. You can hear what’s being said and others can hear what you are saying.

The feature I appreciate most about it though is that the headset section of the system can be detached, via its 3.5mm plug, from the remote control block of the USB section that connects to your PC. Plugged into a mobile phone or tablet, this then becomes a particularly good hardwired (as opposed to Bluetooth) comms headset.

One of the most annoying shortcomings of most hardwired, in-ear headsets—especially the ones that come free with even expensive smartphones—is that the microphones are usually too far from your mouth to pick up a good outgoing signal. The microphone stalk on the MPOWs is semi-rigid and can be adjusted to get up close to your voice.

The earpieces are reasonably comfortable for long use; the control block has volume-up and volume-down buttons—plus a mute button with a clear LED indicator that lights up either blue or red (a better combination for the colourblind than green and red) to tell you its state; and the connection cable is a short, but sensible, length.