make a certain software version the default in ubuntu

Question

I currently have 2 version of php installed on ubuntu 12.04.

one for php 5.3 installed using apt-get while the other one is installed with xampp with php 5.5

When i execute these commands:

> which php
/usr/bin/php

> php --version
PHP 5.3.10-1ubuntu3.8 with Suhosin-Patch (cli) (built: Sep  4 2013 20:05:42) 
Copyright (c) 1997-2012 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2012 Zend Technologies
    with Xdebug v2.2.3, Copyright (c) 2002-2013, by Derick Rethan

>echo $PATH
/home/chanhxc/bin
/usr/lib/lightdm/lightdm
/usr/local/sbin
/usr/local/bin
/usr/sbin
/usr/bin
/sbin
/bin
/usr/games
/opt/lampp/bin
/home/chanhxc/pear/bin
/home/chanhxc/.composer/vendor/bin
/opt/lampp/bin
/home/chanhxc/bin
/usr/lib/lightdm/lightdm
/usr/local/sbin
/usr/local/bin
/usr/sbin
/usr/bin
/sbin
/bin
/usr/games
/home/chanhxc/bin
/usr/lib/lightdm/lightdm
/usr/local/sbin
/usr/local/bin
/usr/sbin
/usr/bin
/sbin
/bin
/usr/games
/opt/lampp/bin
/home/chanhxc/pear/bin
/home/chanhxc/.composer/vendor/bin
/opt/lampp/bin

How do i make php 5.5 the default version to be run?

Btw, my default shell is zsh. here's the line in my .zshrc

export   PATH=$PATH:/home/chanhxc/bin:/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
    # xampp, pear, composer
export PATH=$PATH:/opt/lampp/bin:/home/chanhxc/pear/bin:/home/chanhxc/.composer/vendor/bin:/opt/lampp/bin

Update

If i'm opting for the update-alternatives option. Here's what i currently have.

>update-alternatives --query php
Link: php
Status: auto
Best: /usr/bin/php5
Value: /usr/bin/php5

Alternative: /usr/bin/php5
Priority: 50
Slaves:
 php.1.gz /usr/share/man/man1/php5.1.gz

Solution 1

I think the best way to do this on Ubuntu is like that:

sudo update-alternatives --set php /usr/bin/php5.6

You may change the version according to your needs.

Solution 2

There are a million things you can do instead of changing your $PATH.

One is to define an alias in your /home/YOUR_NAME/.bashrc file,

alias myphp=' /path/to/my/favorite/php ' 

Another one is to rename the version of php that you do not want, and to transform /usr/bin/php in a symbolic link to the version you wish to use:

sudo mv /usr/bin/php /usr/bin/php_5.3.10
sudo ln -s /path/to/php/you/want /usr/bin/php

Or you may use the Debian alternatives system. First, you install a php alternative,

 sudo update-alternatives --install "/usr/bin/php" "php" "/pathto/your/favorite/php" 1 

then you control that everything's fine by means of

sudo update-alternatives --display php

And much, much more.

Solution 3

sudo update-alternatives --config php

Comments

[chanHXC]

thanks for the suggestion. but what's the best way there. i actually have an alias as phplatest with php 5.5 version. would soft linking php in /usr/bin/php makes the other version in xampp be default?

[chanHXC]

btw, what exactly does an update-alternative command do?

[MariusMatutiae]

Keeps tab of which programs, all providing the same service, you prefer to use. Like having Chrome, Chromium, Firefox, Iceweasel on the same pc, which one should open when you click on alink in an e-mail? The one update-alternatives has indicated as the master.

[chanHXC]

ok thanks. but why do i get unknown argument `php'. when executing update-alternatives

[MariusMatutiae]

@chanHXC That's because I made an error in the syntax. I have updated my post, it should now work. Remember to move the existing php to /usr/bin/php_old

[Dave Drager]

I agree that this is the best way to do this. It updates the link in /usr/bin/php to the correct version. In Ubuntu 16 you can install php5.6 and php7.0 and have them running at the same time - which is nice, but sometimes you want to update the default.

[Rolando Isidoro]

This might be more user-friendly as it allows the user to interactively select which of the available alternatives to choose from.