Simlink real-world example

Question

I read php functions and I came across symlink , but I really couldn’t capture it, especially its use in real-world application development. Can someone explain to me the real world example?

thanks

Answer 1

Suppose you have an src folder in the $HOME directory where your sources are stored. When you open a new shell, you usually enter your $HOME directory when the shell starts. This can be a general step, whenever whenever you open a new shell, you want to subsequently enter the ~/src/very_long_project_name .

Symbolic links appear here: you can create a symbolic link in your $HOME directory (for example, called vlpn , which directly points to ~/src/very_long_project_name .

The next time you open the console, you can simply type cd vlpn instead of cd src/very_long_project_name . It. Nothing special about PHP. Like giraff and gnur already said.

Answer 2

The administrator can create symbolic links to organize storage without corrupting file systems; for example, a web mirror can contain thousands of hosted sites, and dozens of drives are installed:

 /mnt/disk1/ /mnt/disk2/ ... 

and you want to store data in your /var/www/htdocs/ without worrying about which drive stores their data.

 /var/www/htdocs/debian -> /mnt/disk1/debian /var/www/htdocs/ubuntu -> /mnt/disk2/ubuntu /var/www/htdocs/centos -> /mnt/disk9/centos 

Secondly, you may have a "last boot"; your users upload photos or software packages, and you want http://example.com/HOT_STUFF always be the most recent photo uploaded. You can set symlink($new_upload, $HOT_STUFF); , and users don’t need more than one URL to see the newest thing.

Thirdly, Debian and Ubuntu use the update-alternatives mechanism to immediately install several versions of the tool and still allow the administrator to specify which one is the default. eg.

 $ ls -l /usr/bin/vi lrwxrwxrwx 1 root root 20 2011-01-11 01:07 /usr/bin/vi -> /etc/alternatives/vi $ ls -l /etc/alternatives/vi lrwxrwxrwx 1 root root 18 2011-01-11 01:07 /etc/alternatives/vi -> /usr/bin/vim.basic $ ls -l /usr/bin/vim.basic -rwxr-xr-x 1 root root 1866904 2010-09-28 04:06 /usr/bin/vim.basic 

This is a bit cool, but the configuration is saved in the directory for each system /etc/ , and the usual path /usr/bin/vi will do what is very similar to vi when there are many options available (nvi, elvis, vim, AT & T vi etc.)

Answer 3

Symbols are what is used on the host OS, and not just on PHP itself.
It creates a shortcut for the file. It may be useful to request a much-used file with a long path by creating a symbolic link in the public_html folder to a long path that you can include in it without using the full path.

http://en.wikipedia.org/wiki/Symbolic_link

//edit:
This is better than just copying the file, because you are really using the original file, so if the original change of the symbolic link always points to a new file, then this is not a copy!

Answer 4

The php function actually delegates only the functionality of the operating system, which is why it is as useful as a symbolic symlink in general:

Symbolic links work transparently for most operations: programs that read or write files, a symbolic link will behave as if directly working with the target file.

(from Wikipedia)

I saw how it was used by Typo3 :

On each Typo3 site there is a folder that links to the main installation - therefore several sites can use the same code base, and Typo3 can be updated by extracting the new version and then changing the symbolic links (reducing the site’s offline life).

Answer 5

here is a pretty good usage example with explanation http://dogmatic69.com/blog/development/12-symlink-cakephp-plugin-assets-for-faster-page-loads