no ip domain-lookup

One of the most annoying features of Cisco's IOS is the assuming that anything you type which is not a command is a hostname. So...

Router#dev
Translating "dev"...domain server (255.255.255.255)
 (255.255.255.255)
Translating "dev"...domain server (255.255.255.255)
....

... and when you are configuring a router which either (a) does not have DNS, (b) is on a network that is down, or (c) is on the workbench and not actually connected to a network - you get to enjoy the long pause of a DNS timeout.

Argh!

Playing With Drive Images

I purchased a copy of Windows 10 on a USB thumbdrive. I chose to have media to have (a) a backup and (b) not to have to bother with downloading a massive image. Primarily this copy of Windows will be used in VirtualBox for testing, using Power Shell, and other tedious system administrivia. First thing when it arrived is I used dd to make a full image of thumbdrive so I could tuck it away in a safe place.

Some Informix DATETIME/INTERVAL Tips

Determine the DATE of the first day of the current week.

(SELECT TODAY - (WEEKDAY(TODAY)) UNITS DAY FROM systables WHERE tabid=1)

Informix always treats Sunday as day 0 of the week. The WEEKDAY function returns the number of the day of the week as a value of 0 - 6 so subtracting the weekday from current day (TODAY) returns the DATE value of Sunday of the current week.

Cut-N-Paste Options Greyed Out In Excel

Yesterday I encountered a user who could not cut-and-paste in Microsoft Excel. The options to Cut, Copy, and Paste where disabled - aka 'greyed out' - in the menus. Seems like an odd condition.

rrdtool lastupdate

A variety of tools use RRD databases which are ideal for recording a sequence of values over time. So one interesting question is when the last time the rrd file was updated - rrdtool's lastupdate mode will tell you.

$ rrdtool lastupdate probe302Value_probe302Value.rrd
1334603585: 190.0

The most recent value in the RRD is 190.0 recorded at 1334603585

The value of the time is a UTC timestamp. Converting this value to a readable date/time can be performed using the UN*X date command.

Which Application?

Which application manages this type of file? How can I, by default, open files of type X with application Y? These questions float around in GNOME forums and mailing lists on a regular basis.

The answer is: gvfs-mime .

yum-config-manager --setopt=

It is common knowledge that on CentOS/RHEL hosts you can enable and disable defined reposities with the yum-config-manager. However it is also possible to use yum-config-manager tool to set any repository parameter using the setopt parameter.

dd REPORT!

dd is an underrated tool. What it lacks in user interface it makes up for with its swiss-army-knife number of purposes; from testing, to secure wiping, to backup and restore. But that user interface... it is bleak.

Stream Peekaboo With Python

The Python standard libary provides a reasonably adequate module for reading delimited data streams and there are modules available for reading everything from XLS and DIF documents to MARC data. One definiciency of many of these modules is the ability to gracefully deal with whack data; in the real world data is never clean, never correctly structured, and you are lucky if it is accurate even on the rare occasion that it is correctly encoded.

For example, when Python's CSV reader meets a garbled line in a file it throws an exception and stops, and you're done. And it does not report what record it could not parse, all you have is a traceback. Perhaps in the output you can look at the last record and guess that the error lies one record beyond that... maybe.

Fortunately most of these modules work with file-like objects. As long as the object they receive properly implements iteration they will work. Using this strength it is possible to implement a Peekaboo on the input stream which allows us to see what the current unit of work being currently processed is, or even to pre-mangle that chunk.

LINUX CA Certificate Deployment

Creating an in house signing [aka CA] certificate is a common practice; this allows you to generate free cerficates for internal use. For Windows hosts distributing this CA certificate to all the clients and relevant servers can be accomplished using Active Directory GPOs. Certificate management on LINUX hosts on the other hand has always been a swamp of tedium where the certificates often need to be configured into each client or service. Recent distributions have eased this process considerably by including a quasi-standardized set of scripts and certificate store locations.

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