ServerBuddies Support Blog

FFmpeg error

After installing FFMpeg , when you execute the command : ffmpeg or ffmpeg -v, you may receive an error.

Resolution :

Execute the following command :

But this value will be cleared once you log off that session.

So it is better to save this value in bashrc.

Tags: error, ffmpeg

Disable direct root login via ssh

Please follow the given steps to disable direct root login access to the server via shell prompt.

STEP 1: Create a user and add it to the wheel group

SSH into your server as root and follow the below commands to create a user.

You can create any user instead of “test”.

STEP 2: Add user to wheel group

You can add the user at the end of the ‘group’ file.

Add the user test:

For CPanel Servers, do the following.

1. Log into your WHM and click on “Manage Wheel Group Users”.

2. Select the user (Here it is “test”) and click ‘Add to group’.

3. Before disable the root access, check if the user can login and su – to gain root privileges.

SSH into your server as ‘test’

Login as: test

Password : enteryouruserpasswordhere

su –

password: enter root password here

STEP 3: Disable Direct Root Login

1. Copy and paste this line to edit the file for SSH logins

2. Find the line

3. Uncomment it (Remove #) and change it to look like

4. Next, find the line

5. Uncomment it (Remove #) and make it look like PermitRootLogin no

6. Save the file.

Now, no one will be able to login to root with out first logging in as ‘test’ and ’su -’ to root.

Tags: direct, Disable, root login, SSH

Yum errors

While running ‘Yum update’, if we get the following error,

We can fix the error by installing GPG public key.

There are few kind of RPMs e.g atrpms, dag..

You can see the RPM types using the command,

Below are the ways to install RPM GPG keys for atrpms and dag,

Tags: errors, yum

Turn on DMA mode on a hard drive

Direct memory access (DMA) allows certain hardware subsystems within the computer to access system memory for reading and/or writing independently of the central processing unit. It uses a procedure called cycle stealing, where the central processor memory access cycles are delayed for very short times to intersperse DMA controller memory access cycles. DMA is used for transferring data between the local memory and the main memory.

You can turn On DMA mode on a hard drive

You can check whether DMA is enabled on a hard drive for the IDE harddrive.

If DMA is on, the output should contain the following line,

If it is off you can enable it as follows,

This will toggle the value of “using_dma” (It will turn off the value of “using_dma” if it was already on).

Tags: DMA mode, hard drive

Change priority of swap files

You can check the current priority of the swap file from /proc/swaps.

Inorder to change the priority of the swap partitions, you need to edit the “fstab” and append the new priority. If you have the fstab entry for your swap file /swap1 as:

then append the following:

where x is the new priority you have set.

You can re-mount it by using ‘mount -a’ command.

Tags: Files, priority, swap