simon.schönbeck.dk

Category: tagged

  • Error: Could not open the local file – FTP madness!

    Trying to move some automatic backups from one location to another became a bit of a struggle recently. The backups are created automatically and uploaded to a file server at a scheduled pattern. From this file server I had to use some of the backups and tried to download them to my local machine. This is where the problem started.

    I am long time user of the excellent FTP client named FileZilla and very seldom experience any issues with it. But this time during the download process I kept receiving this weird error message:

    Error:    Could not open the local file path/filename
    Error:    Download failed

    I initially thought about some permission problems like no read access until I swiftly realised it was actually on the local side the issue was and not on the server. This just made no sense as obviously why would it want to open the file when it actually had to create the file instead. I tried to download the backups to different locations on the hard disks, even external ones as well, to see if oddly enough they had magically become write protected. This was not successful and I started to think of the directory structure as downloading the individual file worked just fine.

    So to summarise:

    1. Downloading the directory containing the backups did not work.
    2. Downloading each individual file inside the directory worked as expected.

    Very strange indeed…

    I actually did not break it until the following morning when I woke up with the solution. I am not sure what happened as I would not dream about such a pity issue but I just woke up and Eureka!

    In hindsight it was really obvious what the problem was but at the point it just did not come to my mind.

    Linux and Windows have some dramatic differences and one of them is the fact that file and directory names under Windows are limited to certain characters while Linux pretty much takes it all. I was trying to download directories to a Windows XP PC with a colon (:) in the name, such as . This is incompatible with Windows and therefore FileZilla was not permitted to create such directories anywhere on the hard disks.

    Never use the following characters in file or directory names if you expect Windows compatibility:

    / \ : * ? " < > |

  • Excel sort by length of string

    I received a question today on how to sort a list of strings which was actually rather simple to accomplish.

    The following list is the original sorting:

    • caca
    • cocacola
    • ca
    • cacacacacola
    • c
    • cacacacacacacaac
    • cacaa

    The requested list after sorting should look like this:

    • c
    • ca
    • caca
    • cacaa
    • cocacola
    • cacacacacola
    • cacacacacacacaac

    What I first did was to create a separate column to contain the length of each cell. There is a function in Excel which easily calculates the length of a string: LEN(). Now I had two columns, the first unsorted string column and the second length (of the first column string) column. As you probably have realised by now it was a simple matter of sorting the second column instead of the first for the strings to sort by length.

    If interested in seeing it I have attached the test sheet for you to play around with:

    Length String Sorting

  • What is a Kill-Bit?

    After booting up Windows XP I encountered an automatic update notification. During the progress I noticed an update named something like “…kill-bit ActiveX…” which I could not identify what was for and therefore looked it up.

    The Kill-Bit appears to be something as simple as a registry entry to disable vulnerable ActiveX controls or COM objects so they can no longer be loaded in Internet Explorer or other applications based on the MSHTML rendering engine.

  • Virtualmin scheduled backups strftime usage

    I have been using Virtualmin for several years which is one of the greatest modules for Webmin allowing simple set-up and management of virtual hosts. Inside the “Scheduled Backup” feature I came across the “Do strftime-style time substitutions on file or directory name” check box but never actually properly made use of it:

    Virtualmin Scheduled Backup

    I came across a project which required very frequent backups and to distinguish each backup from another I decided to give it a shot. The strftime function uses standard POSIX conversion specifications which very easily lets you build powerful combinations of date and time.

    As an example you can use the following string:

    /backup_%Y_%m_%d_%H.%M

    which would leave a directory with the following name:

    Now each backup will be created with a different name instead of simply overwriting the previous one.

  • AVG 8 LinkScanner crashes Firefox

    After upgrading to the latest version of the free anti virus application from AVG I encountered constant crashes of Firefox. It seems that AVG 8 includes a utility called LinkScanner which marks whether a website is supposedly a threat or safe upon using a search engine:

    AVG LinkScanner ThreatAVG LinkScanner No Threat
    I am not the biggest fan of these utilities as many false positives arise plus the user ends up losing his own
    criteria and relies solely on the utility’s advice instead of thinking and evaluating each site by himself. Nevertheless it may be suitable for complete beginners as a helping hand.

    Firefox did start to behave erratically after the AVG upgrade from version 7.5 to 8 so there was no real doubt about why it was happening, so I immediately disabled the LinkScanner component within the AVG user interface. This seemed to be the only part that could affect the browsers somehow:

    AVG LinkScanner disabled

    Firefox stopped crashing and all was fine again. There was just a little thing that kept nagging me. The little red exclamation mark by the clock in the traybar kept displaying now. It was not possible to know whether there was an update waiting or any other issue as the exclamation sign was on constantly. I ended up turning LinkScanner on again just to remove the exclamation.

    Back to Firefox crashing…!

    Until today when I again got so tired of the continuous crashes that I finally searched for the problem and located a very simple solution to it.

    Simply leave the LinkScanner component running so you do not get the annoying exclamation mark. Now launch Firefox and go to Tools > Add-ons and disable the AVG add-on. This would disable the AVG 8 LinkScanner component without interfering with anything else on your PC.