DNS – simple and effective guide with history

Here is link to a very nice and definitive guide to DNS. Very detailed and useful. There is a pdf version as well to download 🙂

https://webhostinggeeks.com/guides/dns/

Thanks to Andrijana Nikolic for providing a valuable resource to share with you all.

virsh – show ip address of all running VMs

If you are using the libvirt and associated tools, then you must be aware about virt-manager. However this being a GUI tools, it is not possible to always use this. “virsh” is a good option for this.

To start with, if you need to know all the VMs all the running VMs, then you can use (to only view the names):

virsh list --name

Extending this to make it more useful is the case if you need to know the IP address for the running VMs. Here is a simple code that you can put in alias or function that can be used to get the IP address of the running VM’s.

image ordering by Original Date Time using bash script

Here is the script:

#!/bin/bash -
#===============================================================================
#
#          FILE: imgOrg.sh
#
#         USAGE: ./imgOrg.sh
#
#   DESCRIPTION:
#
#       OPTIONS: ---
#  REQUIREMENTS: ---
#          BUGS: ---
#         NOTES: ---
#        AUTHOR: Amit Agarwal (aka)
#      REVISION:  ---
#===============================================================================

for i in *
do
    if [[ $(file $i) == *image* ]] 
    then
        echo "Image file is :: $i"
        dir=$( exiftool -s -DateTimeOriginal $i | awk -F':' '{print $2"/"$3}')
        mkdir -p $dir
        cp $i $dir/
    else
        echo "Excluding $i"
    fi
done

Disk usage by file type

Trying to find the total usage for each of the file types by extension, then here is a quick bash function for you :

disk_usage_type () 
{ 
    find . -name '*'$1 -ls | awk '
    BEGIN{
        a[0]="Bytes";
        a[1]="KB";
        a[2]="MB";
        a[3]="GB";
    }
    {sum+=$7; files++;}
    END{
    print "Total sum is ::\t" sum;
    print "Total files  ::\t" files;
        while (sum > 1024) {
            sum=sum/1024;
            count++;
            };
        print sum" "a[count];
    }'
}

Just define the function in one of your bash startup files. After that to use the function pass in the extension for which you would like to find the total size. Output should be something like below:

terminal, terminal everywhere.

Tilda is a borderless terminal that can be started multiple times each with its own configuration.

Name        : tilda

Arch        : x86_64

Epoch       : 0

Version     : 1.2.4

Release     : 1.fc23

Size        : 344 k

Repo        : @System

From repo   : fedora

Summary     : A Gtk based drop down terminal for Linux and Unix

URL         : http://github.com/lanoxx/tilda

License     : GPLv2+

Description : Tilda is a Linux terminal taking after the likeness of many classic terminals

from first person shooter games, Quake, Doom and Half-Life (to name a few),

where the terminal has no border and is hidden from the desktop until a key is

pressed.

 

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How to verify sha256sum for multiple file or one file.

So, lets say you have downloaded the SHA256SUMS files. This file contains the sha256sum for multiple files and you want to compare the values for only one or some of them, then the simplest thing you can do is:

sha256sum -c SHA256SUMS

Now, with this if you do not have some files present then you might get some errors and if you do not want that, then you can try this:

Get count of lines in scripts (shell)

If you have tried to get the count of lines in file, the you would know about “nl” or “wc -l”. But as you are aware these give you number of lines with other details as well and you need to post process the number to make sure that you have only number and nothing else. In such cases, it is useful to use the count feature of grep and here is a shorthand to get the count of lines in any shell script: