[TipJar] Quickly wipe a file in a Linux shell

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No time to read through contexts? Jump to the TL;DR; section.

There are use cases that require the secure wiping or deletion of files. There are already a lot of available utilities available in most modern distributions such as srm, swipe, etc. These however entail installing an additional package which is fine for work machines. The use case I had is to securely delete a transient file after it was generated and used in a Continuous Integration server. Installing the secure-delete package is trivial but a base Linux system already has the tool that can do the job: dd

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Sync clock with Google

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If the Linux VM was running at the time the host OS (Windows) hibernated then the clock in the guest VM will be left at the time of hibernation. If NTP is configured then the clock should resync gradually but most systems do not apply a big chunk of time correction by default.

If the Linux VM was configured with a VPN that implements a system-wide configuration then the DNS resolution might be unable to resolve the NTP server since the DNS of the VPN session will be unavailable. The alternate and work-around presented hinges on two things:

  • The guest VM has internet access at the time it was resumed.
  • The google.com domain name is already resolved and cached.

   sync-clock() {
     echo Current time before sync: `date`
     echo Current time after sync : `sudo date -s "$(wget -qSO- --max-redirect=0 google.com 2>&1 \ 
       | grep Date: | cut -d' ' -f5-8)Z"`
    }

The work-around uses the time in the google headers to provide an anchor for the correction.  This is provided as a bash function to provide user feedback if a correction was done.

Snippet execution

Fix for crashing gnome-control-center

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The GNOME control center in my Manjaro system crashed while I was tweaking the details of the mouse settings. After it crashed, I was unable to bring it up again even after a reboot.

The solution was to reset the configuration files for it using the following command:

$ dconf reset -f /org/gnome/control-center/

After that, the control center UI is up and running again. Based on the search hits, visiting the details pane can sometimes caused the state that results to a segmentation fault whenever the control center initializes.

We welcome our new overlords

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I heard in a Technology training that “It is hard to comprehend that there will come a time that Artificial Intelligence (AI) will get smarter than us humans but it may still be about 50 more years.”

I find that preposterous. AI by definition isnt going to be smarter than human intelligence. It doesnt need to be. Humans on the other hand will just grow dumber. Technology helps.

Docker image cleanup

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Running docker frequently can lead to mysteriously disappearing space. I kid, its not mysterious. Each image builds a layer which in turn eats up space. Logical but PITA!

Put this in your .bashrc or run it as cron on your docker host to clean up.


docker rm -v $(docker ps -a -q -f status=exited)
docker rmi $(docker images -f “dangling=true” -q)

or do it in one alias (use at your own discretion)


alias docker_janitor='docker rm -v $(docker ps -a -q -f status=exited);docker rmi $(docker images -f “dangling=true” -q)'

sounds too easy..

ciao!

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