Useful aptitude commands

Linux, , , , , ,

A simple list of installed packages

max@wonko:~$ aptitude search '~i' -F '%p'

Search for installed packages from the testing repo

max@wonko:~$ aptitude versions '~i ~Atesting' --group-by=none

Finding why a package is installed

I found fonts-font-awesome in my headless server, but there’s a reason

max@wonko:~$ aptitude why fonts-font-awesome
i   owncloud Depends fonts-font-awesome

Select packages that were removed but not purged

max@wonko:~$ aptitude search '~c'

Search in the package description

max@wonko:~$ aptitude search '~d"web browser"'

Upgradable packages

max@wonko:~$ aptitude search '~U'

How to enable/disable Android logcat when using a custom kernel

Android, How to, , , , ,
A good source of information could be found in this page, but none of them worked for me.

The most useful article I found was on xda and here’s the solution:

  • enable 
    echo 0 > /sys/module/logger/parameters/log_mode
  • enable at boot, but not when suspended 
    echo 1 > /sys/module/logger/parameters/log_mode
  • completely disabled: 
    echo 2 > /sys/module/logger/parameters/log_mode

(you need a rooted device)

How to compile rsync for Android in Ubuntu

Android, How to, Linux, Programming, , , , , , , ,

My situation

My machine

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 14.04 LTS
Release:    14.04
Codename:   trusty

The latest rsync version to compile (for me it was rsync-3.1.0.tar.gz)

$ curl -s http://rsync.samba.org/ftp/rsync/ \
    | sed -r 's/^.*href="([^"]*)".*$/\1/' | grep 'rsync-[0-9].*\.tar\.gz$'

Procedure

  1. save the tarball name in a variable 
    $ RSYNCTGZ="rsync-3.1.0.tar.gz"
  2. install needed software 
    $ sudo aptitude install gcc-arm-linux-gnueabi
  3. download sources 
    $ wget http://rsync.samba.org/ftp/rsync/$RSYNCTGZ
$ tar xzf $RSYNCTGZ
$ cd rsync-[0-9]*
  4. compile 
    $ ./configure --host=arm-linux-gnueabi CFLAGS=-static
$ make
  5. install on the device 
    $ adb push rsync /data/local/tmp && adb shell chmod 775 /data/local/tmp/rsync
  6. test execution 
    $ adb shell /data/local/tmp/rsync

References

Override DNS for KitKat – first release

Android, Override DNS, Programming, , , ,

Override DNS for KitKat has been released

Override DNS icon

Override DNS is the easiest way to force your rooted phone to use custom nameservers on mobile networks.

Many things dealing with name resolution have changed in Android 4.4 KitKat and so all the current Play Store apps stopped working.

The problem I found with this release of Android (4.4) is that, apparently for caching reasons, the system behaviour has been changed to redirect all DNS queries to a system daemon called netd (here’s a link to a presentation related to Android networking before 4.4 which, however, covers part of this topics).

The getprop/setprop method used by all the DNS changer apps does not work anymore. Those values, when changed, get simply ignored by the netd daemon.

It’s necessary to communicate directly to the daemon via the /dev/socket/netd socket.

The app automatically guesses the network device name and applies the right commands each time a mobile network gets activated.

How to display PHP errors only in public_html directories

How to, Linux, Programming, Uncategorized, web, , , , , , , , , ,

How to display PHP errors

I always use servers where PHP errors are not shown by default and I always forget how to enable error messages in development environments.

My situation

On a server I usually prefer Debian OS, but when I develop on the go I use laptops with Ubuntu.
In this case I’m running Ubuntu 14.04 LTS with Apache2 (v2.4.7) and libapache2-mod-php5 (v5.5.9).

I want PHP errorors displayed for projects in my public_html folder.

Solution 1 (only Apache conf files)

Create the file /etc/apache2/sites-enabled/800-public-html.conf with this content:

<Directory /home/*/public_html>
  AllowOverride Options
  php_admin_flag display_errors On
</Directory>

Solution 2 (using .htaccess)

Create the file /etc/apache2/sites-enabled/800-public-html.conf with this content:

<Directory /home/*/public_html>
  AllowOverride Options
</Directory>

Create the file /home/max/public_html/project1/.htaccess with this content:

php_admin_flag display_errors On

Conclusions

It’s easy and easily forgettable. Don’t forget to add

error_reporting(E_ALL | E_NOTICE);

in your .php files.