Thursday, December 23, 2021

RabbitMQ How to Purge All Queues ?

 There are some situations where you may need to clear or purge all messages from a queue. 

Using Command Line:

You can purge or clear a queue with the following command:


$ rabbitmqctl purge_queue queue_name

Purge Queue from the Web UI

Click on the Queues tab.

Click on the name of the queue that you want.

Expand the “Purge” section.

Click the “Purge Messages” button.

Click “OK”.

Purging all queues 

$ rabbitmqadmin -f tsv -q list queues name > list1.txt

$ for i in `cat list1.txt`; do rabbitmqctl purge_queue "$i" ; done 

Tuesday, April 27, 2021

How to Install XAMPP on linux ?

 What is XAMPP?

XAMPP is the most popular PHP development environment.

XAMPP is a completely free, easy to install Apache distribution containing MariaDB, PHP, and Perl.

Download the latest version from here


After download change the permission :

chmod 755

sudo ./

If it linux server Press all Yes during installation. 

If it is the desktop version of linux press next during installation. 

Now need to change the permission for htdocs :

cd /opt/lampp/

chmod -R 777 htdocs

cd htdocs

create one demo.php file and write code :


echo “Welcome to linux for freshers” 


To start the XAMPP service :

sudo /opt/lampp/lampp start

Starting XAMPP for Linux 7.4.16-0...

XAMPP: Starting Apache...ok.

XAMPP: Starting MySQL...ok.

XAMPP: Starting ProFTPD...ok.

To run the php file:




To stop the XAMPP service:

sudo /opt/lampp/lampp stop

Stopping XAMPP for Linux 7.4.16-0...

XAMPP: Stopping Apache...ok.

XAMPP: Stopping MySQL...ok.

XAMPP: Stopping ProFTPD...ok.

Friday, April 23, 2021

how to send broadcast messages to all currently logged on users in linux ?

 Wall displays the contents of a file or, by default, its standard input, on the terminals of all currently logged-in users. The command will cut over 79 character long lines to new lines. Short lines are white space padded to have 79 characters. The command will always put the carriage return and new line at the end of each line.

Only the super-user can write on the terminals of users who have chosen to deny messages or are using a program that automatically denies messages.

Reading from a file is refused when the invoker is not a superuser and the program is suid or sgid.

Usually, system administrators send messages to announce maintenance and ask users to log out and close all open programs. The messages are shown to all logged-in users with a terminal open.


wall [-n] [-t timeout] [message | file]

The most straightforward way to broadcast a message is to invoke the wall command with the message as the argument:


wall "The system will be restarted in 10 minutes."


Broadcast message fromroot@linuxforfreshers (pts/0) (Mon Jan  4 13:22:07 2021):

The system will be restarted in 10 minutes.

The message will be broadcasted to all users that are currently logged in.

To suppress the banner and show only the text you types to the logged-in users, invoke the command with the -n (--nobanner) option:


wall -n "The system will be restarted in 10 minutes."


The system will be restarted in 10 minutes.

If you want to write multi-line messages, invoke the command without an argument:


The wall command will wait for you to enter text. When you’re done typing the message, press Ctrl+D to end the program and broadcast the message.

You can also use the here-string redirection or pipe the output of another command to wall. Here is an example showing how to use the echo command to broadcast multi-line messages:


echo "The system will be restarted in 10 minutes. \nPlease save your work."  | wall


Broadcast Message from root@linuxforfreshers                                       

        (/dev/pts/1) at 13:36 ...                                              


The system will be restarted in 10 minutes. \nPlease save your work.        

Broadcasting a Message From a File 

If you are regularly sending the same messages, you can write each one of them to a file, so that you don’t need to re-type the same text. wall reads from the file only when invoked as root.

To broadcast the contents of a file, invoke the wall command followed by the file name:

cat message1_file.txt

The system will be restarted in 10 minutes.


wall message1_file.txt


Broadcast message from root@linuxforfreshers (pts/0) (Mon Jan  4 13:30:07 2021):

The system will be restarted in 10 minutes.

Thursday, April 8, 2021

How to change python default version in ubuntu?

 In ubuntu By default python version was 2.7. We need to use python3 to run the python files with the latest version.

Steps to change the default python version to 3

Check the current version 

#python --version

Python 2.7.17

Execute this command to switch to python 3.6. 

#sudo update-alternatives --install /usr/bin/python python /usr/bin/python3 1


sudo update-alternatives --install /usr/bin/python python /usr/bin/python3 1

update-alternatives: using /usr/bin/python3 to provide /usr/bin/python (python) in auto mode

Check python version

python --version

Python 3.6.9

Tuesday, April 6, 2021

How to Install innotop in linux?

Innotop is an efficient command-line monitoring tool for local and remote MySQL servers running under Innodb. It helps to monitoring several operations like MySQL replication status, user statistics, query list, InnoDB buffers, InnoDB I/O information etc.

To Install Innotop

Run the following command to install Innotop

In RedHat

yum install innotop

In Ubuntu

Fetch innotop from its GIT repository:

Install Perl dependency:

sudo apt install libterm-readkey-perl libclass-dbi-perl libclass-dbi-mysql-perl make 

sudo apt-get install git

git clone



cd innotop/

perl Makefile.PL

Note:If there no warnings and errors (in case you have to fix other dependencies), proceed with the installation of this good MySQL InnoDB real-time monitor:

sudo make install

Innotop can be launched in several ways, the easiest is to provide, on the command line, username and password (with -u [user] and -p [password]) of a privileged user.


sudo innotop -uuser -ppassword

Now the terminal will be logged in.

Press " ?" help symbol to view the various option available.

To Monitor the remote mysql server

If you want to monitor the remote mysql server, run the below command. Login the remote mysql server enter the mysql username, password and hostname.

sudo innotop -uuser -ppassword -hip_address

Wednesday, March 24, 2021

How to find the file size of a remote HTTP object?

There are times when you need to know the file size of an HTTP object without actually downloading the file. This little trick comes in very handy when web servers respond with the Content-Length of an object in the HEAD request itself.

Using curl command:


curl -sI | grep Content-Length

Content-Length: 2877227008

Let’s try and make this human-friendly:

curl -sI | grep Content-Length | sed 's/[^0-9]//g' | numfmt --to=si


Where The Numfmt command will convert the numbers to/from human-readable format.