Quick and dirty reboot of remote Linux server

It sounds annoying sometimes when I was rebooting the remote Linux server, especially on the Cloud. After issuing command like:

$
$ reboot now

The terminal session will definitely be disconnected but the server still hangs in the middle of the termination process and would not boot-up.

We can hard reset the machine if we are sitting in front of it. Holding down [Alt] and [SysRq] (which is the Print Screen key) while slowly typing keys R, E, I, S, U, B will get you safely restarted. Meanings of the keys as follows:

•     R: Switch the keyboard from raw mode to XLATE mode
•     E: Send the SIGTERM signal to all processes except init
•     I: Send the SIGKILL signal to all processes except init
•     S: Sync all mounted filesystems
•     U: Remount all mounted filesystems in read-only mode
•     B: Immediately reboot the system, without unmounting partitions or syncing

For the cloud server, we definitely need some sort of Terminal commands to put the server strictly into reboot process no matter what process is currently running or hanging. At least, we can diagnose it after it boots up again.

$
$ echo 1 > /proc/sys/kernel/sysrq
$ echo b > /proc/sysrq-trigger

First command mimics the keystroke of System Request [SysRq] key and the second one mimics hitting [b] key.

So, [b] for what? It does immediately reboot the system, without unmounting partitions or syncing

So just be prepared, you may suffer any data loss afterwards. However, it's really useful at the time you want to make sure the server does reboot immediately.

*A suggestion would be manually stopping major services and processes before you issue such commands.

XRDP Login with Black Screen issue

After trying a couple of things on the Linux server and found nothing wrong with the configuration of XRDP server, I was wondering what exactly caused this whereas I got used to login properly without any issue with RDP client on Mac OS X.

Is it something wrong with an update on Microsoft RDP client, or something deep inside my connection profile?

Just found this a reply on the forum which points me to the right direction.

According to the replies in the forum
http://sourceforge.net/projects/xrdp/forums/forum/389417/topic/4880098,
it looks like a problem in the domain settings in my connection profile which has been remembered since I connected to some other servers whereas a domain needs to be specified. In Preference, I simply cleared the field Domain and now my XRDP session can be connected again with no further issue.

Apart from the black screen, here's our login session window again!

The same thing may happen on Windows RDP client as well. So, please beware of the Domain when logging in XRDP next time.

PHP Accelerator for XAMPP on Linux

Since PHP 5.3 was released, it had been even harder to find stable accelerator to boost up the performance. Recently, I searched through the news and blogs about any breakthrough of PHP accelerator and found some good news. One of those package called APC has released new packages which claimed to fully support PHP 5.3. So far it has good responses among the users regarding stability and performance. Also, APC is going to be deployed as built-in accelerator in PHP 5.4 soon.

To install new package of APC from the scratch, we need something more installed on Linux platform:

Packages required:
Autoconf: Whatever version is fine.
XAMPP: Version from 1.7.2 to 1.7.7 should be okay.
XAMPP development source: This must be corresponding to the original version of XAMPP package.
APC: Latest APC package available for the best support.

To install Autoconf on Linux, like Ubuntu:

#
$sudo apt-get install autoconf

To install XAMPP:
Download and install XAMPP package from http://www.apachefriends.org/en/xampp-linux.html

#
$wget http://www.apachefriends.org/download.php?xampp-linux-1.7.7.tar.gz

$sudo tar xvfz xampp-linux-1.7.7.tar.gz -C /opt

Of course, you need to finish the basic setup and make sure Apache server and MySQL are running before you proceed to the following steps.

To install XAMPP development source:
Use the following link and modify version of XAMPP pacakge as required.
Here, assuming we have installed XAMPP 1.7.7 package:

#
$wget http://www.apachefriends.org/download.php?xampp-linux-devel-1.7.7.tar.gz




$sudo tar xvfz xampp-linux-devel-1.7.7.tar.gz -C /opt

To compile and install APC source:
#Download and extract source files

#
$wget -O APC-latest.tar.gz http://pecl.php.net/get/APC

$tar xvfz APC-latest.tar.gz

$cd APC-*

#run phpize while in APC source directory

#
$sudo /opt/lampp/bin/phpize

#Configure source with setting appropriate config path pointing to XAMPP php-config file

#
$sudo ./configure --with-php-config=/opt/lampp/bin/php-config

#Compile and install

#
$sudo make

$sudo make install

Now, add new line into php.ini and restart Apache server to initialize APC module:

#
$sudo sh -c "echo 'extension=apc.so' >> /opt/lampp/etc/php.ini"

$sudo /opt/lampp/lampp stopapache



$sudo /opt/lampp/lampp startapache

To check if APC is running, type the following command:

#
$sudo /opt/lampp/bin/php -r 'echo phpinfo();' | grep apc --color

And then you should see some related information about running APC module when things don't go wrong.