How to free RAM Memory

STEP1:

    i) sudo sync

  ii)sudo sysctl -w vm.drop_caches=3

  iii) sudo sync




STEP2:


  i) echo 1 > /proc/sys/vm/drop_caches

  ii) echo 2 > /proc/sys/vm/drop_caches

  iii) echo 3 > /proc/sys/vm/drop_caches

how to install pandas in python

We find difficulty in installation and pandas mainly when there are multiple versions of python installed on system to avoid confusion use below command:

python -m pip install pandas python -c 'import pandas'

You may replace word 'python' with exact version of python also, if required, eg:

  python3.8 -m pip install pandas 

  python3.8  -c 'import pandas'  

Error: /usr/bin/ld: cannot find -lfl

Error: /usr/bin/ld: cannot find -lfl
collect2: error: ld returned 1 exit status
Makefile:69: recipe for target 'unified' failed
make: *** [unified] Error 1

Solution: sudo apt-get install flex

How to install libsndfile and Armadillo library on ubuntu

Installation of libsndfile:

sudo apt-get install libsndfile-dev

Installation of Armadillo

1.  If not present already, install LAPACK, Boost and BLAS  with 

   sudo apt-get install liblapack-dev  sudo apt-get install libblas-dev  sudo apt-get install libboost-dev

2. Install Armadillo using 

   sudo apt-get install libarmadillo-dev

How to disable directory listings on apache running on Ubuntu

open /etc/apache2/apache2.conf

And the section of the settings that deals with listing directory in Apahce2 default root directory is this:

<Directory /var/www/>  Options Indexes FollowSymLinks  AllowOverride None  Require all granted  </Directory>  

To disable directory listing, edit the setting to be this:

<Directory /var/www/>  Options FollowSymLinks  AllowOverride None  Require all granted  </Directory>  

Save the file and restart Apache2 to load the new configuration settings.

How to disable Web server version disclosure

On Debian, Ubuntu or Linux Mint:

$ sudo vi /etc/apache2/apache2.conf

On CentOS, Fedora, RHEL or Arch Linux:

$ sudo vi /etc/httpd/conf/httpd.conf

Add the following two lines at the end of Apache config file.

1 2	ServerSignature Off ServerTokens Prod

Then restart web server to activate the change.

Ref: http://ask.xmodulo.com/turn-off-server-signature-apache-web-server.html

Protocol "'http" not supported or disabled in libcurl

Error: Protocol "'http" not supported or disabled in libcurl

Solution:

Ensure you are supplying curl with double quotes ("), not single quotes (')