Tag Archives: ubuntu

How to display PHP errors only in public_html directories

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.

Cache deb packages with apt-cacher-ng

I’m playing with Docker and I’m constantly tuning my Dockerfile to install the needed packages.

This continuous refinement forces the build process to download the same deb packages every time and it becomes an actual waste of time and bandwidth.

Solution

apt-cacher-ng is a service which can be run on a Debian or Ubuntu host and will serve as a local cache for deb packages from Debian or Ubuntu repositories.

That’s what I need because I’m on an Ubuntu machine emulating a Debian container.

Host setup

The setup is really easy:

# aptitude install apt-cacher-ng

After the installation I changed the bind address of the service to keep it local (I don’t need LAN exposure), I added my local proxy to reach the internet and I disabled ReuseConnections (see Problems):

root@yoda:/etc/apt-cacher-ng# diff acng.conf acng.conf.old 
28d27
< BindAddress: localhost 172.17.42.1
35d33
< proxy: http://127.0.0.1:5865
322d319
< ReuseConnections: 0

Client setup

On the client side it’s necessary to force apt requests to use the proxy.
In the Dockerfile I added

RUN echo 'Acquire::http::Proxy "http://172.17.42.1:3142";' > /etc/apt/apt.conf.d/90-apt-cacher.conf

which creates the configuration file read by apt-get or aptitude when downloading packages.

Problems

The apt-cacher-ng server seems buggy at least when used in conjunction with a regular proxy. Sometimes I get errors like these on the client side

Err http://http.debian.net/debian/ wheezy/main netbase all 5.0
500  Invalid header

one possible solution is to perform a

# apt-get update

on the host machine (it seems to help). Another useful setting is

ReuseConnections: 0

as explained before.

HP ProBook 4540s brightness control in Ubuntu 13.10

The HP ProBook 4540s is a good choice when you need a GNU/Linux machine, but there are some hit and miss on the details. The thing I found most tedious is the brightness controls using the keyboard: they simply don’t work at all.

My soloution

See the kernel parameters actually used:

$ cat /proc/cmdline 
BOOT_IMAGE=/boot/vmlinuz-3.11.0-15-generic root=UUID=8850c025-676a-4e8c-ac83-4ed1147b88d4 ro quiet splash vt.handoff=7

If there’s no reference to acpi_backlight, that’s the problem. Add the parameter to /etc/default/grub changing the following line from

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

to

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

Done