Linux Installations

1. Start a remote SSH session or access a GUI terminal window (Konsole in KDE, Gnome Terminal in Gnome, etc.)

2. Use one of the following commands to stop the buagent service:

# /etc/init.d/cdp-agent stop

or

# service cdp-agent stop

3. Create the empty file /usr/sbin/r1soft/.recovery-mode:touch /usr/sbin/r1soft/.recovery-mode
as shown:

4. And last, save the /etc/init.d/buagent file, and restart the agent service.

/etc/init.d/cdp-agent start

or

service cdp-agent start

This will successfully place the Linux R1Soft Agent into recovery mode.

I have seen recent cPanel upgrade from old version 11.24 to 11.30 and got the following error.

# /scripts/upcp
/scripts/upcp syntax OK
Running Futex Check/Fix……Done
Undefined subroutine &Cpanel::Update::automatic_updates_enabled called at /scripts/upcp line 273.

This can be fixed using below :

wget -O /root/updatenow.static http://httpupdate.cpanel.net/cpanelsync/RELEASE/scripts/updatenow.static && perl /root/updatenow.static --manual

Upgrade the cPanel :

/scripts/upcp --force

it should be work perfect.

Regards

Alex P

This post looks at what caused the issue and how to fix it.

Clearly there’s something wrong with the way phpmyadmin sessions are being used. Cpanel work with is own internal PHP and store the application session files in different folder for security reason.

On Cpanel server, every application as his own php configuration setting like phpmyadmin , php configuration file is /usr/local/cpanel/3rdparty/etc/phpmyadmin/php.ini , roundcube (/usr/local/cpanel/3rdparty/etc/roundcube/php.ini)

PHPmyAdmin session files are store in /var/cpanel/userhomes/cpanelphpmyadmin/ folder.  The /var/cpanel/userhomes/cpanelphpmyadmin/ folder ownership should be cpanelphpmyadmin.cpanelphpmyadminn  /var/cpanel/userhomes/cpanelphpmyadmin/ in order to get phpmyadmin work perfect.

root@server [/var/cpanel/userhomes]# chown cpanelphpmyadmin.cpanelphpmyadmin cpanelphpmyadmin/ -R

If session folder owned by any other username rather than cpanelphpmyadmin then you will get “Cannot start session without errors, please check errors given in your PHP and/or webserver log file and configure your PHP installation properly” error.

root@server [/var/cpanel/userhomes]# ll
drwxr-xr-x  4 cpanel           cpanel            4096 Dec 11 23:04 cpanel/
drwx--x--x  4 cpanelhorde      cpanelhorde       4096 Sep 24  2009 cpanelhorde/
drwx--x--x  4 cpanelphpmyadmin cpanelphpmyadmin  4096 Sep 24  2009 cpanelphpmyadmin/
drwx--x--x  4 cpanelphppgadmin cpanelphppgadmin  4096 Sep 24  2009 cpanelphppgadmin/
drwx--x--x  4 cpanelroundcube  cpanelroundcube   4096 Sep 24  2009 cpanelroundcube/
root@server [/var/cpanel/userhomes]#

Regards

Alex P

Whenever you are trying to upload an image using the flash uploader in WordPress and received a “HTTP error”? and uploading images status stuck in crunching ……..

Here solutions::

The problem has something to do with mod_security, which is basically a web application firewall that protects your website from a range of attacks. So you shouldn’t turn off this module as it protects your site from such malicious attack , You can add a special rule in .htaccess file which can be found in the root folder of your WordPress installation to get work the flash uploader.

Open the .htaccess file in your website document root and add the following lines:

• For Apache 1.X
  

  <IfModule mod_security.c>
  <Files async-upload.php>
  SecFilterEngine Off
  SecFilterScanPOST Off
  </Files>
  </IfModule>

• For Apache 2.X
  

  <IfModule mod_security2.c>
  <Files async-upload.php>
  SecRuleEngine Off
  SecAuditEngine Off
  </Files>
  </IfModule>

Then try to upload the images it should be work like charm D:

First you will have to uninstall/remove exiting RoundCube files/folder/database on your server,

• Uninstall/remove exiting RoundCube

cd /usr/local/cpanel/base
rm -rf roundcube*
mysql -e 'drop database roundcube';
/scripts/upcp

Now follow the following steps to  update/install latest roundcube  version ,we need to get Roundcube before we can use it. The easiest way to get it is to visit http://www.roundcube.net and click on “Downloads” or just go to http://roundcube.net/downloads. Wait for it to download and then unzip (using WinZip or ZipGenius or tar -xzf roundcubemail-0.1.tar.gz) in the current directory.

• update/install latest roundcube

cd /usr/local/cpanel/base
wget -O roundcube.tar.gz http://nchc.dl.sourceforge.net/sourceforge/
roundcubemail/roundcubemail-0.2.1.tar.gz
rm -rf roundcube.tar.gz
mv -f roundcubemail-0.2.1/ roundcube
cd roundcube
chmod -R 777 temp
chmod -R 777 logs

• Database Configuration

Create the database, database user and install the intial sql file. The following commands will do this for you.

mysql -e "CREATE DATABASE roundcube;"
mysql -e "GRANT ALL PRIVILEGES ON roundcube.* TO roundcube@localhost IDENTIFIED BY
'DATABASEPASSWORD';"
mysql -e "FLUSH PRIVILEGES;"
mysql -e "use roundcube; source SQL/mysql.initial.sql;"

You will have to replace the roundcube password with ‘DATABASEPASSWORD’ field.

• Configuring RoundCube

cd config
mv db.inc.php.dist db.inc.php
mv main.inc.php.dist main.inc.php

then open database configruation file  db.inc.php in your favroite editor like vi or pico or nano
vi db.inc.php
Find following line

$rcmail_config['db_dsnw'] = 'mysql://roundcube:pass@localhost/roundcubemail';

Replace it with

$rcmail_config['db_dsnw'] = 'mysql://roundcube:DATABASEPASSWORD@localhost/roundcube';

Now Open main.inc.php

vi main.inc.php

Find

$rcmail_config['default_host'] = '';

Replace with

$rcmail_config['default_host'] = 'localhost';

Last steps , restart the mysql, cpanel services on your server. That’s it ,Have fun with your new Roundcube installation!!

Regards

AlexP

memcached is a high-performance memory object caching system intended to speed up dynamic web applications by alleviating database load.

memcached is meant to work in concert with something like the MySQL query cache, not replace it. The two implementations excel at vastly different things: memcached is an object cache, while MySQL provides a query cache.

memcached is extremely fast. It uses libevent, which provides a mechanism to execute a callback function when a specific event occurs on a file descriptor, to scale to any number of open connections. On a modern Linux system memcached utilizes epoll, is completely non-blocking for network I/O, ensures memory never gets fragmented, and uses its own slab allocator and hash table to achieve 0(1) virtual memory allocation.

How it install it on Linux server ?

• Install dependency software (Libevent)

#curl -O http://monkey.org/~provos/libevent-1.4.9-stable.tar.gz
#tar -xzvf libevent-1.4.9-stable.tar.gz
#cd libevent*
#./configure
#make
#make install

• Now let’s download the newest Memcached source

#curl -O http://www.danga.com/memcached/dist/memcached-1.3.0.tar.gz
#tar zxf memcached-1.3.0.tar.gz
#cd memcached-1.3.0
#./configure
#make
#make install

• Then add /usr/local/lib to LD_LIBRARY_PATH in your .bash_profile

LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib
export LD_LIBRARY_PATH

How it Works

First, you start up the memcached daemon on as many spare machines as you have. The daemon has no configuration file, just a few command line options, only 3 or 4 of which you’ll likely use:

Run Memcached as a daemon (d = daemon, m = memory, u = user, l = IP to listen to, p = port)

#memcached -d -m 1024 -u root -l 127.0.0.1 -p 11211 –u nobody

This starts memcached as a daemon (-d) on the IP address and port specified with -l and -p, respectively, running as the user nobody (-u), allocating 1024  for object storage (-m). You should adjust the amount of storage to suit your needs; many memcached installs run with 4 GB. Once you are comfortable with your startup options, add the appropriate command to your startup scripts.

Create a /etc/init.d/memcached file and add above line to start memcached when the server boots

With memcached installed and running, it’s time to get PHP talking to the object cache. While multiple PHP API exists, the one in the PECL repository is recommended. If you are running a newer version of PHP, installation is as simple as:

# pecl install memcache

Or you can use following steps to install PECL memcache manually.

#cd /usr/local/src
#curl -O http://pecl.php.net/get/memcache
#tar zxvf memcache*
#cd memcache-*
#phpize
#./configure
#make && make install

Now we have to make sure PHP loads the newly built memcache.so library by adding the following line to php.ini:

extension=memcache.so

Now restart Apache:

Service httpd restart

Once it sucussfully install you can create phpinfo() on your webserver should now confirm that memcache is installed.

Regards
AlexP

Svn(subversion) is used to maintain current and historical versions of files such as source code, web pages, and documentation. Its goal is to be a mostly-compatible successor to the widely used Concurrent Versions System (CVS).

It is very easy to install subversion client on linux OS using yum. You can us following command to install subversion client.

root@server [~]# yum install subversion

while installing subversion if you are getting following error  then it seem sot be perl-URI package is not installed on your server so you will have to install first before installing subversion client.

Please follow the following steps to install perl-URI package

You’ll login via SSH as root and run this command:

root@server [~]# yum install subversion

and then you may get this error:

Error: Missing Dependency: perl(URI) >= 1.17 is needed by package subversion

Here’s what you do next (copy/paste):

root@server [~]# wget  ftp://ftp.pbone.net/mirror/archive.fedoraproject.org/
fedora/linux/releases/7/Everything/i386/os/Fedora/
perl-URI-1.35-3.noarch.rpm 

root@server [~]# rpm -i perl-URI-1.35-3.noarch.rpm

root@server [~]# yum install subversion

Installed: subversion.x86_64 0:1.4.2-4.el5 subversion.i386 0:1.4.2-4.el5

Dependency Installed: neon.x86_64 0:0.25.5-10.el5 neon.i386 0:0.25.5-10.el5

Complete!

That’s it subversion client is successfully installed on your server you can check it using following command.

root@server [~]#svn --version
svn, version 1.1.4 (r13838)
compiled Aug 21 2005, 20:56:55

Copyright (C) 2000-2004 CollabNet.
Subversion is open source software, see http://subversion.tigris.org/
This product includes software developed by CollabNet (http://www.Collab.Net/).

The following repository access (RA) modules are available:

* ra_dav : Module for accessing a repository via WebDAV (DeltaV) protocol.
- handles 'http' schema
- handles 'https' schema
* ra_local : Module for accessing a repository on local disk.
- handles 'file' schema
* ra_svn : Module for accessing a repository using the svn network protocol.
- handles 'svn' schema

Regards

Alex P

How can you do that ?

After installing suhosin, remove all functions from disable_functions in php.ini and add in php.ini suhosin.executor.func.blacklist = “exec,passthru,shell_exec” and all the functions that you want to disable globally.

After that for each domain in the virtual host section you can add suhosin.executor.func.blacklist again but without the function that you need to enable. And so you will enable that function only for one domain.

Example:

<VirtualHost 127.0.0.1>
………..
………..
<IfModule mod_php4.c>
php_admin_value open_basedir “/usr/lib/php”
</IfModule>
<IfModule mod_php5.c>
php_admin_value open_basedir “/usr/lib/php”
php_admin_value suhosin.executor.func.blacklist = “passthru,shell_exec”
</IfModule>
…….
……
</VirtualHost>

In this example exec has been enabled for the VirtualHost. This way it will be better as you do not neet to modify all the virtual hosts only the ones that you need to enable one or more functions.

Regard’s

Alex P

What is mod_ruby?

mod_ruby embeds the Ruby interpreter into the Apache web server, allowing Ruby CGI scripts to be executed natively. These scripts will start up much faster than without mod_ruby.

1) Install eRuby

# wget http://www.modruby.net/archive/eruby-1.0.5.tar.gz
# tar -xzvf eruby-1.0.5.tar.gz
# cd eruby-1.0.5/
# ./configure.rb –with-charset=euc-jp –enable-shared
# make; make install

2) Install mod_ruby

i)Download latest mod_ruby tar file
# wget http://www.modruby.net/archive/mod_ruby-1.2.6.tar.gz
# tar -xzvf mod_ruby-1.2.6.tar.gz
# cd mod_ruby-1.2.6/
#  ./configure.rb –enable-eruby –with-apxs=/usr/local/apache/bin/apxs
# make; make install

ii)Edit apache configuration file ( httd.conf) and add following code

LoadModule ruby_module libexec/mod_ruby.so
ClearModuleList
AddModule mod_ruby.c
AddHandler cgi-script .rb
<IfModule mod_mime.c>

# for Ruby/eRuby
<IfModule mod_ruby.c>
# for Apache::RubyRun
RubyRequire apache/ruby-run
# for Apache::ERubyRun
RubyRequire apache/eruby-run
# for development
# RubyRequire auto-reload
# for add library
#RubyAddPath /usr/local/lib/ruby
# exec *.rbx as ruby scripts.
<Files *.rbx>
SetHandler ruby-object
RubyHandler Apache::RubyRun.instance
</Files>
# handle *.rhtml as eruby files.
<Files *.rhtml>
SetHandler ruby-object
RubyHandler Apache::ERubyRun.instance
</Files>
</IfModule>
</IfModule>

iii) Restart apache service on server

Regards

Alex P

Hello,

I was facing same error with one of my shared server last couple of week, apache was broke on server and getting following error in apache error logs file.

[emerg] (28)No space left on device: Couldn't create accept lock

[notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)

[notice] Digest: generating secret for digest authentication ...

[notice] Digest: done

[warn] pid file /etc/httpd/run/httpd.pid overwritten -- Unclean shutdown of previous Apache run?

[emerg] (28)No space left on device: Couldn't create accept lock

I checked disk space, or quota limit but everything was fine. I through it seem to apache semaphore problem

Apache can create the “accept lock” is with a semaphore. A semaphore is an inter-process communication tool that is used by Apache to communicate with it’s child processes. This error message may mean that Apache couldn’t create a new semaphore.

Check to see how many semaphores are currently in use. If Apache is running correctly, you should see something like this:

# ipcs -s

If Apache is stopped, and you still see these semaphores, then you can safely kill them by running this command for each semaphore id (in the second column)

$ ipcrm -s <semid>

To destroy all semaphores, you can run this from the command line (with “apache” being the apache-user:

for semid in `ipcs -s | grep apachec | cut -f2 -d" "`; do ipcrm -s $semid; done

OR

ipcs -s | grep apache | perl -e ‘while (<STDIN>) { @a=split(/\s+/); print `ipcrm sem $a[1]`}’

OR

ipcs -s | grep nobody | perl -e ‘while () { @a=split(/\s+/); print `ipcrm sem $a[1]`}’
ipcs -m | grep nobody | perl -e ‘while () { @a=split(/\s+/); print `ipcrm -m $a[1]`}’

OR
for i in `ipcs -s | awk ‘/httpd/ {print $2}’`; do (ipcrm -s $i); done

How to increase semaphore limit

To view the current parameters:

ipcs -l

To change these parameters, modify the file /etc/sysctl.conf and add the following lines:

kernel.msgmni = 1024

kernel.sem = 250 256000 32 1024

Then load these settings with the command:

sysctl -p

Regards

StacyM

System Administrator