Roby Firnando Yusuf's questions

I've got stucked for 4 days on installing openCV.always got error while compile the source code. I assume because libtiff5-dev not installed on my machine, then I tiedy to install libtiff5-dev, here is the output :

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 libtiff5-dev : Depends: liblzma-dev but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

said "depends liblzma-dev", then I tried to

$ sudo apt-get install liblzma-dev

but error too, here is the output :

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 liblzma-dev : Depends: liblzma5 (= 5.1.1alpha+20120614-2ubuntu2) but 5.2.2-1.3~16.04.york0 is to be installed
E: Unable to correct problems, you have held broken packages.

anyone have solution for this problem ?

i've been install PHP7.2 on my PC but when i try to php -v it's show me error like this

bash: /usr/local/bin/php: No such file or directory

and then i try to type php7.2 -v it's works

Anyone have solution so when i type php -v it's show me php7.2 ?

i've been uninstall php5.6 on my PC then I upgrade to PHP7.2 but when i checked php cli php -v, it's show me like this, it's still show me PHP 5.6

Anyone can help me out ?

i have installed 2 php versions on my PC here, i run this command

composer require kreait/firebase-php ^4.18

but that show error message :

[InvalidArgumentException]
Package kreait/firebase-php at version ^4.18 has a PHP requirement incompat
ible with your PHP version (5.6.20)

when i run phpinfo it's said php7.2 but when i check php -v it said php5.6 anyone can help me out and why it's happen ?

I've been installed PHP7.1 and my on my laptop has 2 php versions there are PHP 5.6 and PHP7.1 , i tried a2dismod php5.6 and a2enmod php7.1 then i restarted .. and i tried php -v still show me old version , anyone have solution about this ?

Thank you

I want to change color of the left sidebar

Can anyone help me out?