Virtual Box Start Error (VNC)

I went to start my Windows XP virtual machine, after something like ~4 years. And it failed to start with an 0x80004005 error: "Could not find the VirtualBox Report Desktop Extension library." Hmmm, that's strange.

Turns out that the extensions loaded by the Windows XP VM uses the library libvncserver which was no longer installed on the host. Unfortunately the VirtualBox Extensions are not integrated into the distribution's package manager.

Dropping An Element In An Iterative Parse

Using lxml's etree to iteratively parse an XML document and I wanted to drop a specific element from the stream...

        for event, element in etree.iterparse(self.rfile, events=("end",)):
            if (event == 'end') and (element.tag == 'row'):
                self.wfile.write(etree.tostring(element))
            elif (event == 'end') and (element.tag == name_of_element_to_drop):
                element.getparent().remove(element) # drop element

The secret sauce is: element.getparent().remove(element)

Installing The Zoom Client On openSUSE 15.1

Uh oh, in a default-ish GNOME install of openSUSE 15.1 there are a couple of unmatched / unclaimed dependencies. It appears Zoom Inc. did not try very hard when drafting the spec for their LINUX clients.

gEdit's Amazing External Tools

In a few recent conversations I have become aware of an unawareness - an unawareness of the awesome that is gedit's best feature: External Tools. External Tools allow you to effortlessly link the power of the shell, Python, or whatever into an otherwise already excellent text editor yielding maximum awesome. External Tools, unlike some similar features in many IDEs is drop-dead simple to use - you do not need to go somewhere and edit files, etc...

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Uncoloring ls (2019)

This is an update from "Uncoloring ls" which documents how to disable colored ls output on older systems which define that behavior in a profile.d script.

PostgreSQL: "UNIX Time" To Date

In some effort to avoid time-zone drama, or perhaps due to fantasies of efficiency, some developer put a date-time field in a PostgreSQL database as an integer; specifically as a UNIX Time value. ¯\_(ツ)_/¯

How to present this as a normal date in a query result?

PostgreSQL: Casted Indexes

Dates in databases are a tedious thing. Sometimes a time value is recorded as a timestamp, at other times - probably in most cases - it is recorded as a date. Yet it can be useful to perform date-time queries using a representation of time distinct from what is recorded in the table. For example a database which records timestamps, but I want to look-up records by date.

To this end PostgreSQL supports indexing a table by a cast of a field.

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Listing Printer/Device Assignments

The assignment of print queues to device URIs can be listed from a CUPS server using the "-v" option.

The following authenticates to the CUPS server cups.example.com as user adam and lists the queue and device URI relationships.

Reprinting Completed Jobs

Listing completed jobs

By default the lpstat command lists the queued/pending jobs on a print queue. However the completed jobs still present on the server can be listed using the "-W completed" option.

For example, to list the completed jobs on the local print server for the queue named "examplep":

Create & Deleting CUPs Queues via CLI

Create A Print Queue

[root@host ~]# /usr/sbin/lpadmin -U adam -h cups.example.com:631 -p examplelm1 -E \
  -m "foomatic:HP-LaserJet-laserjet.ppd" -D "Example Pick Ticket Printer"\
   -L "Grand Rapids" -E -v lpd://printer.example.com/lp

This will create a queue named examplelm1 on the host cups.example.com as user adam.

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