To show currently mounted partition in human readable format, use:
df -h
Another way to check partition information using parted.
sudo parted /dev/sda print
Here, we can see that the disk size is 120GB along with the partition information.
To view the list of partitions using fdisk, use:
fdisk -l
To view the list of block devices:
lsblk
Hope this helps! Cheers 🙂
Lets look at passing arguments to an alias by looking at an example.
The below command will open duckduckgo.com in a new tab in firefox.
firefox --new-window duckduckgo.comLets say, I want to create an alias but I want to pass the URL as a parameter to the alias.
For example, if I run the following command in the terminal, it should look at the first argument (which is the URL) and open it in a newtab in firefox.
ff duckduckgo.com
To achieve this, you can do the following:
Edit your ~/.bashrc or ~/.bash_profile using your favorite editor.
vim ~/.bashrc
Create a function inside the ~/.bashrc with the following content. [Copy/paste the below inside your bashrc]
alias ff='function _ff()
{
firefox --new-window $1
};_ff'Here, $1 is the first argument.
Once you save and close the bashrc file, you can source your bashrc for changes to take affect.
source ~/.bashrc
Now, if you enter the following command in the terminal, it will take “duckduckgo.com” which is the 1st parameter and open it in a new tab in firefox.
ff duckduckgo.com
Hope this helps. If you like my content, do share and subscribe for more content.
Source: StackOverFlow
This is a guide on how to install aws cli utlity in Linux along with screenshots.
Requirements:
– Linux.
– Python 2.6.5 or higher.
[Tested on Linux Mint with bash shell. should work on Ubuntu as well.]
Update your system and its packages:
sudo apt update && sudo apt upgrade -y
Install Pip:
sudo apt install python-pip -y sudo pip install --upgrade pip
Install the following modules:
sudo pip install setuptools sudo pip install wheel
Install AWS CLI:
sudo pip install awscli
To verify that the installation went well, you can run the following command.
aws --version
If the output shows the aws version, then you are all set.
Enable AWS commands Auto completion:
-To enable auto completion of sub commands, run the following to check where your “aws” and “aws_completer” are located.
which aws which aws_completer
-Copy the output of “which aws_completer”. This would the path.
For example, if the output of “which aws_completer” was “/usr/local/bin/aws_completer”, then enter the following:
complete -C '/usr/local/bin/aws_completer' awsHeres a screenshot reference:
Verify if AWS command auto completion works:
-Run the following command and press press TAB on your keyboard after typing “ec” and it should give you the possible options:
aws ec
Add path to your .bashrc or .bash_profile:To make the changes persistant for aws command completion, you can add the following to your “.bashrc” or “.bash_profile.
echo "complete -C ‘/usr/local/bin/aws_completer’ aws" >> ~/.bashrcHope this helps! 🙂
Regards,
ΞXΤЯ3МΞ
Here is a screenshot of my terminal when I open tmux:
Note: Here, my shell displays my username@hostname but it does not display it in colors 🙁
To make tmux read your bash colors, edit your tmux configuration file:
vim ~/.tmux.conf
Add the following line to the tmux config file:
set -g default-terminal "screen-256color"
Exit and save the file. Close and re-open tmux.
Now, when you open tmux you should be able to get your regular bash prompt colors. Here is a screenshot after re-opening tmux:
Hope this helps! Cheers!
Source: Link
This a tutorial on how to get real time currency exchange rates directly from your Linux terminal (+ lots of screenshots).
Requirements:
-A computer ( *facepalm* 😛 )
-Any Linux/Windows machine with curl installed.
-Free account with openexchangerates.org
We will be using the “curl” utility to perform the API requests which usually comes pre-installed in most Linux systems.
In case, yours does not have it installed, you can install it using the following:
[You can run “apt install curl” for Ubuntu based systems, or “yum install curl” for RHEL/CentOS/Fedora based systems or “dnf install curl” for newer Fedora systems.]
Step 1: Sign up for a free account in openexchange. You can use the below link:
https://openexchangerates.org/signup/free
I would suggest to create an account with a new password that you have never used before.
[Note: The free account has restrictions but should be sufficient to get latest conversion rates with base currency set as USD. With the free account we cannot change the base currency. This means with the free account you can translate 1USD to any other currency. I will create a different tutorial describing another method to get ]
Step 2: Get your APP ID
-Once you sign up for the account, you would receive an email with a verification email which will have your “APP ID”. Below is a screenshot:
You would need to get this ID when performing the API call.
-Alternatively, once you have signed up you get your API key once you login to your account. Below is a screenshot:
Step 3: Get exchange rates:
-Open your terminal and run the following command:
curl -X GET https://openexchangerates.org/api/latest.json?app_id=enteryourAPIKEYhere
Enter your app ID after “=”. For example, if your APP ID is 1234, them you would run the following:
curl -X GET https://openexchangerates.org/api/latest.json?app_id=1234
Below is a sample output which displays the different currencies and its conversion values.
You would notice the output is in JSON format which has values in keypairs. (For example: the “currency name”: “value”.)
The data that is pulled is in realtime and it also displays the “timestamp” for which the currency converstions are in linux EPOC time.
Additional Information:
To know the current EPOC time in your system, you can command “date +%s” in your terminal. This is the number of seconds since 1970-01-01 00:00:00 UTC.
For simplicity, If you are looking to convert USD to a particular currency, you can simply grep the output with the currency you need to convert to.
For example: If you convert 1 USD to INR, you can simply grep the currency name to filter out the output.
curl -s -X GET https://openexchangerates.org/api/latest.json?app_id=1234 | grep INR
Below is a screenshot of the outputs.
Thats it folks! Hope this helps! If you liked this tutorial, leave a comment down below and follow to get future updates ! 🙂
This is a guide on how to check if a partition is primary in centos or not? Use the following command:
# parted /dev/sda print
Alternative:
# cfdisk /dev/sda
As shown above, the field under “Part Type” would suggest if that partition is Primary/Secondary.
To exit out of the cfdisk menu, use your arrow keys and move the selection to “Quit” and hit Enter in your keyboard.
Source: Link
As always stay Happy! Happy Blogging! 🙂
ΞXΤЯ3МΞ
If your host PC (in my case Windows 10) is connected to a VPN but your CentOS 6.x VM is not using the VPN, then do the following:
1: Power off your CentOS VM.
2: Right click your centos machine in virtualbox and then click “Settings“.
3: Click “Network” and change the Adapter Settings to “NAT“.
4: Now power on your centos virtual machine.
5: Once your VM boots up, login and then restart the network service. You can use the following CLI command “service network restart“.
Your CentOS virtual machine should now to able to use the VPN connection and use it accordingly. Do verify the same in your virtual machine. Hope this helps!
Do like and subscribe if this guide helped you. Cheers!
This guide on how to protect against Off-path TCP vulnerability CVE-2016-5696 in a CentOS 6.8 machine.
Run the following command to check the kernel version that your box is running:
uname -r
Run the following to verify your Centos version details:
cat /etc/redhat-release
Below is a screenshot for the outputs for the above commands from my CentOS 6.8 box.
Open your sysctl.conf file:
vi /etc/sysctl.conf
Below is a screenshot of my default sysctl.conf file which does not contain “net.ipv4.tcp_challenge_ack_limit”.
Now add the following line at the end of the config file:
net.ipv4.tcp_challenge_ack_limit = 999999999
Below is a screenshot after editing the config file.
Save and exit the file. (Press ESC and then type :wq and hit Enter in your keyboard).
Use the command below to verify if the value of net.ipv4.tcp_challenge_ack_limit is 999999999.
sysctl -p
If you are able to see the line in the above screenshot, this means that it will make the exploit extremely hard to perform (practically impossible). The above is a workaround to mitigating the Off-Path TCP attack in a CentOS 6.8 machine and will also work for redhat 6.8.
If you are not looking for the workaround but for a permanent fix, then you can upgrade your Linux kernel to 4.6 or above.
If this article helped you, do leave a comment below and like us on Twitter and Facebook. Cheers!
Source: Bobcares
References: Redhat Portal, Redhat Shared Ack Vulnerability
This is quick guide on how to use netcat (nc) to chat between two PCs over LAN.
VM 1: CentOS 6.6
My CentOS machine did not have netcat (nc) preinstalled so I had to manually install it.
# yum install nc -y
VM 2: Kali Linux 2016.1 | IP: 192.168.1.11 |
The Kali Linux 2016.1 had netcat tools were pre-installed so i didn’t have to install it. Here, we take any one of the 2 Pcs as the chat server and the other as the chat client.
Here, I am selecting the Kali Linux to listen for connections on a random port 12345. [Note: The port you select must be higher than the standard port 1024.]
In this case, I will make Kali as the chat server and set it to listen on port 12345.
# nc -lvp 12345
Now from the 2nd PC i.e. the CentOS machine, we will make a connection to the Kali machine on port 12345.
# nc 192.168.1.11 12345
Once connected, Kali’s terminal would show as message such as shown below:
Now, to start chatting type the text and hit ENTER in your keyboard to send chat messages between the two PCs. Pretty sweet uh?
FYI, There are practically tons of uses of netcat (nc) other than sending messages.
Other uses of netcat:
Have you found any another use with netcat? Post it in the comment section down below. If your on a Linux machine, check out the man page for netcat for more info. Happy exploring!
If you liked this article, don’t forget to subscribe and follow us on Twitter and Facebook.
Source: Cybrary.it
If you need to read a file and print from a range of line numbers (including the last one), you can use the command as shown below.
cat <filename> | awk 'NR >=linenumber1 && NR <=linenumber2'
To read and display a file along with the line numbers, you can use the following format:.
cat -n <filename>
Example:
cat -n sample.txt
For example:
To print lines starting from line 2 to line 7, then you can use the following command.
cat sample.txt | awk 'NR >=2 && NR <=7'
Sample Output:
If for any reason you need to display the line numbers along with the output, then you can pass the -n argument to cat before piping it to awk as shown below.
cat -n sample.txt | awk 'NR >=2 && NR <=7'
Sample Output:
[Note: There are multiple methods to do the same procedure. This method is intended for beginners who are just getting started in Linux.]
Hope this helps!
If this article helped you, do leave a comment below and like us on Twitter and Facebook. Cheers!
Source: Link
