07 August 2015

Uninstall Package di Ubuntu Linux


  • apt-get remove packagename
    will remove the binaries, but not the configuration or data files of the package packagename. It will also leave dependencies installed with it on installation time untouched.
  • apt-get purge packagename or apt-get remove --purge packagename
    will remove about
    everything regarding the package packagename, but not the dependencies installed with it on installation. Both commands are equivalent.
    Particularly useful when you want to 'start all over' with an application because you messed up the configuration. However, it does not remove configuration or data files residing in users home directories, usually in hidden folders there. There is no easy way to get those removed as well.
  • apt-get autoremove
    removes orphaned packages, i.e. installed packages that used to be installed as an dependency, but aren't any longer. Use this after removing a package which had installed dependencies you're no longer interested in.
  • aptitude remove packagename or aptitude purge packagename (likewise)
    will also attempt to remove then not used dependencies anymore in one step.
And many more exist. Lower-level dpkg-commands can be used (advanced), or GUI tools like Muon, Synaptic, Software Center, etc. There's no single 'correct way' of removing applications or performing other tasks interacting with your package management.
The list you found are just examples. Make sure you understand the meanings and try out what it wants to do before accepting the action (you need to press Y before it actually performs the actions as proposed).
The asterisk version in the question is probably wrong; apt-get accepts a regular expression and not a glob pattern as the shell. So what happens with
sudo apt-get remove application*
is the following:
  1. The shell try to expand application* looking at the files in the current directory. If (as normally is the case) find nothing, it returns the glob patter unaltered (supposing bash with default behavior here --- zsh will error out).
  2. apt-get will remove the packages whose name contains a string that satisfy the regular expression application*, that is, applicatio followed by an arbitrary number of n: applicatio, application, applicationn, libapplicatio, etc.
  3. to see how this can be dangerous, try (without root for double safety) apt-get -s remove "wine*" (-s will simulate the thing instead of doing it) --- it will say is going to remove all packages that has "win" in their name and the dependant, almost all system...
Probably, the command that was meant is really
 sudo apt-get remove "^application.*"
(note the quotes and the dot) which will remove all packages whose name starts with application.
These commands,
sudo updatedb                  # <-- updates the locate database (index). harmless
sudo locate application        # <-- locates the file 'application'. harmless
sudo rm -rf (file/folder name) # <-- removes files/dirs recursively. dangerous.
are completely outside the scope of the package management. Do not remove files belonging to packages without using the package management! It will get confused and is the wrong way to do things.
If you don't know to which package a file belongs, try this:
dpkg -S /path/to/file


05 August 2015

Meyimpan Session PHP pada MySql


Berikut adalah rangkuman bagaimana menjadikan mysql sebagai session storage PHP.

Tujuan menggunakan mysql sebagai session storage adalah:
  1. Penggunaan lebih dari satu web server. Biasanya digunakan untuk menjaga ketersediaan layanan jika sebuah web server menjadi padat dan beban dapat dialihkan ke web server yang lain. (load balancing).
  2. Meningkatkan keamanan pada shared hosting. Penyimpanan session pada file sistem shared hosting dapat meningkatkan resiko keamanan. 

Referensi session storage pada mysql:
Chris Shiflett, Storing Sessions in a Database >> http://shiflett.org/articles/storing-sessions-in-a-database
Sitepoint, Writing Custom Session Handlers >> http://www.sitepoint.com/writing-custom-session-handlers/

Kode: