Drush installation problem I've twice followed these instructions to install Drush 8.
At the end of the process I can run Drush anywhere and it responds as expected.

However, whenever my server connection is broken and I log back into the server, Drush no longer responds.

Can anyone point out why that is happening?

MORE DETIALS:

I honestly don't know what the issue is. I get the following message each time I go through the process of reinstalling Drush:

sisko@localhost:~/bin/drush-master$ drush
No command 'drush' found, did you mean:
 Command 'rush' from package 'rush' (universe)
drush: command not found


I tried another tutorial attempting to install it manually with no success - just the message I pasted above.

I tried running sudo apt-get install drush and it was not found.

If it helps, I am running PHP 7.0.22 on ubuntu 17.04 as shown in the following (and I'm trying to install drush for a Drupal 7 site):

sisko@localhost:~/bin/drush-master$ php -v
PHP 7.0.22-0ubuntu0.17.04.1 (cli) (built: Aug  8 2017 22:03:30) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2017 Zend Technologies
    with Zend OPcache v7.0.22-0ubuntu0.17.04.1, Copyright (c) 1999-2017, by Zend Technologies


The server shell:

sisko@localhost: echo $SHELL
/bin/bash


UPDATE:
I am still experiencing the persistent loss of the Drush command on my server each time the ssh connection drops.
I then have to re-introduce the Drush command by following these steps as detailed by @Sarika:

echo $PATH ---&gt; confirms Drush is **NOT** included in the path
export PATH="$HOME/.composer/vendor/bin:$PATH"
source ~/.bashrc
sudo composer global require drush/drush:8.*
Did you get drush installed on your system? Check it with the following command.

drush --version


If it is a lower version please update drush using composer, if composer already installed skip the step to install composer.

cd ~
curl -sS https://getcomposer.org/installer | php
export PATH="$HOME/.composer/vendor/bin:$PATH"
source ~/.bashrc
composer global require drush/drush:8.*
drush --version