Tag Archives: linux

Searching text on multiple files in Linux

To search for certain text inside multiple files in Linux we can use ‘grep’ command, here is how i do it:

So for example you want to find all .php and .conf files inside the directory “config” that contain the word “mysql” the command should look like this:


Virtualbox VT-x is not available error after upgrade to 4.3.4

I just upgraded my Virtualbox from 4.2.18 to 4.3.4 on my Windows 7 host, upgrade went smooth and without problem.

When i tried to start virtual machines i got VT-x is not available. (VERR_VMX_NO_VMX) error on all of my VMs.

My PC’s processor doesn’t have VT-x hence the “Acceleration” tab on VM’s Settings > System is greyed out so there is no way i can change it from GUI. Virtualbox does run well on version 4.2.8 so i find it strange that 4.3.4 give error that VT-x is not available.

To fix this i had to run commands from command prompt:

Change <vmname> with the name of your VMs from the list in Virtualbox.

Installing Debian 7 on HP ProLiant ML350 G5

Today i tried to install Debian 7 64-bit on a HP ProLiant ML350 G5 server and having problem with its network card firmware/driver not included with Debian 7 installation CD.

The driver for bnx2 was not included because it’s a non-free firmware/driver, hence i ended with Debian installation without network connection.

After a search on Google, i found another CD image on Debian website which contains non-free firmware/driver that you can find and download here: http://cdimage.debian.org/cdimage/unofficial/non-free/cd-including-firmware/

Can’t Create or Write on /tmp With Error: No space left on device

I just got a problem with writing error on /tmp on one of my client server. The strange problem is that df -h command shows that /tmp only 35% used so there should be plenty of space to write on.

After some investigation it seems that the /tmp partition hit the number of files limit due to caching files from nginx filling up /tmp, hence it’s not possible to create new files. This problem cause PHP scripts on Cpanel server to show error regarding session as by default Cpanel installation, PHP session are written in /tmp.

Clearing nginx cache files seems to fix the problem. To prevent this from happening again I setup a cron job to clear nginx cache regularly.

Minimum Install VNC Remote Desktop Server on Centos

I wrote an update for an article that i wrote a couple months ago here It’s a tutorial to install VNC on Linux Centos VPS. On that tutorial I was installing the group package of Gnome Desktop which will install all Gnome’s applications including Open Office. This of course requires a lot of space and RAM resources to be run on a VPS which most of the time we don’t need Open Office etc.

My self only use the VNC server that I installed in a VPS located in US datacenter to access some website which only available for US visitors. For browsing purposes I only need Gnome minimum install and Firefox browser and that is what I installed on this tutorial.

You can read my tutorial here: Minimum Install VNC Remote Desktop Server on Centos

This is why there are 32 bit packages on 64 bit Linux Centos

I just installed a new server with Linux Centos 64 bit installed and noticed that actually some 32 bit packages was also installed when I’m running yum upgrade. There was nothing wrong in YUM configuration that I can find.

It turns out that the reason for those 32 bit packages being installed is that Centos follow the upstream source, hence the 64 bit (x86_64) installation by default will also install 32 bit packages. Since I want to have pure 64 bit system then I remove all 32 bit packages that installed on my server and set the exclude option so that 32 bit will not installed by yum command.

To remove all 32 bit packages run the command:

Continue reading This is why there are 32 bit packages on 64 bit Linux Centos

Modify the Maximum Emails a Domain Can Send per Hour

On Cpanel’s Tweak Settings you can limit the maximum each domain can send out per hour. The problem is that this limit also applies to Mailman mailing list hence causing problem for mailing list owners.

The problem happen when the mailing list has members more than the maximum number of email a domain can send per hour. Once the mailing list hit the max limit, the emails start to be bounced back or dropped by Exim from its queue.

To fix this problem administrator can set a limit for a specific domain on the server by modifying /var/cpanel/maxemails file and add the domain that want its limit to be override:

Then run /scripts/build_maxemails_config to apply the new limit.