Bajar la versión de kernel que se quiere utilizar y ubicarlo en /usr/src

cd /usr/src
wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.28.tar.gz
tar xvzf linux-2.6.28.tar.gz
cd linux-2.6.28

Comenzar la configuración del kernel con una interfaz hecha con ncurses. Es necesario tener instalado el paquete libncurses5-dev.

make menuconfig
make-kpkg clean
make-kpkg --initrd kernel_image kernel_headers

Instalar los paquetes de debian que se habrán creado en el directorio superior.

cd ..
dpkg -i linux-image-2.6.28.7_2.6.28.7-10.00.Custom_i386.deb
dpkg -i linux-headers-2.6.28.7_2.6.28.7-10.00.Custom_i386.deb

Ahora solo queda reiniciar con el nuevo kernel, no es necesario modificar nada en el gestor de arranque.

En ocasiones especiales, mas bien complicadas, es necesario reiniciar un equipo pero no están disponibles los binarios para tal efecto, como podría ser reboot. En ese caso tenemos una sencilla alternativa.

Para realizar un reinicio:

echo b > /proc/sysrq-trigger

Para apagar el equipo:

echo o > /proc/sysrq-trigger

Possible options:

Use xargs. Xargs pass a list of arguments to a command. This deletes all the files listed:

ls |xargs rm

Use find. You can use the find command to make some actions with the found elements.

find . -exec rm {} \;

If you don´t remember any of the above options, always can remove the whole directory and create it again. Caution with the subfolders!

A fatal error has occurred
Could not connect to database for SQL SessionHandler.
Details have been logged for the administrator.

There are some different reasons that causes this error. This is a checklist to solve the problem.

First, check the /etc/my.cnf and remove skip-innodb if its in there.

Second, repair Horde database

mysqlcheck --auto-repair horde

Third, enter mysql and check what socket file is using mysql:

# mysql
mysql> show variables like 'socket';

You must see something like this:

socket /var/lib/mysql/mysql.sock

Edit the config file:

vi /usr/local/cpanel/base/horde/config/conf.php

Change the following two lines from:

$conf['sql']['hostspec'] = 'localhost';
$conf['sessionhandler']['params']['hostspec'] = 'localhost';

to:

$conf['sql']['hostspec'] = 'localhost:/var/lib/mysql/mysql.sock';
$conf['sessionhandler']['params']['hostspec'] = 'localhost:/var/lib/mysql/mysql.sock';

The cause is that Plesk can´t write in the temporal folder specified to storage backups because the owner is root:

ll /var/lib/psa/dumps/
drwx------ 9 root root 4096 Apr 1 14:21 tmp

To fix this change the ownership of the folder:

chown psaadm.psaadm /var/lib/psa/dumps/tmp

Now you can do backups in Plesk.

En determinadas ocasiones si no se tiene acceso a un navegador web puede resultar complicado comprobar los datos de un certificado SSL. Esta operacion que es trivial con cualquier navegador, puede resultar algo mas compleja desde la consola.

Si tratamos de visualizar un certificado ssl con cualquiera de las herramientas habituales para mostrar texto, nos encontraremos con unas cuantas lineas con caracteres incomprensibles similares a estos:

-----BEGIN CERTIFICATE-----
MIIFcDCCBFigAwIBAgIQGDFbr68WSxIWTD8wU9UAZTANBgkqhkiG9w0BAQUFADCB
3DELMAkGA1UEBhMCR0IxFzAVBgNVBAoTDkNvbW9kbyBMaW1pdGVkMR0wGwYDVQQ
...
-----END CERTIFICATE-----

Para conocer los datos del certificado y comprobar que todo esta correcto podemos utilizar la herramienta openssl:

openssl x509 -noout -text -in www.dominio.com.crt

First edit the config file /usr/local/cpanel/base/3rdparty/phpMyAdmin/config.inc.php

Then, change the two following lines from

$cfg['Servers'][$i]['socket'] = ”;
$cfg['Servers'][$i]['connect_type'] = 'tcp';

to

$cfg['Servers'][$i]['socket'] = '/var/lib/mysql/mysql.sock';
$cfg['Servers'][$i]['connect_type'] = 'socket';

Finish restarting mysql

/etc/init.d/mysql restart

The problem:

# ll /var/spool/exim/db/wait-remote_smtp
-rw-r----- 1 root root 12288 Mar 26 06:00 /var/spool/exim/db/wait-remote_smtp

Easy fix:

# chown mailnull.mail /var/spool/exim/db/wait-remote_smtp
# ll /var/spool/exim/db/wait-remote_smtp
-rw-r----- 1 mailnull mail 12288 Mar 26 06:00 /var/spool/exim/db/wait-remote_smtp

Can't do setuid (cannot exec sperl)

In Debian install perl-suid

apt-get install perl-suid

In Centos install perl-suidperl

yum install perl-suidperl

This problem happens when you try to log in PHPMyAdmin in this scenario:

lsattr /usr/local/cpanel/base/3rdparty/phpMyAdmin/config.inc.php
----i-------- config.inc.php
ls -l /usr/local/cpanel/base/3rdparty/phpMyAdmin/config.inc.php
-rwx------ 1 cpanel cpanel 36109 Nov 10 2006 config.inc.php

The solution:

chattr -i /usr/local/cpanel/base/3rdparty/phpMyAdmin/config.inc.php
chgrp cpanel-phpmyadmin /usr/local/cpanel/base/3rdparty/phpMyAdmin/config.inc.php