Markus Blog

Synchronizing Server Date and Time Using rdate

You can sync or update the date and time of your linux server by using rdate command. rdate command will the check the time server and compare the date time on your server to the time server.

If there is time difference, rdate will update your server date time. To update your server date time run this command:

rdate -s <timeserver></timeserver>

The list of time server can be found on this website: http://www.eecis.udel.edu/~mills/ntp/clock1a.html use the one that near with your server location.

Since my server is in Singapore then I use this command:

rdate -s nets.org.sg

To set the hardware clock to match with your system clock, you can use this command:

/sbin/hwclock --systohc

Website Speed Test

How fast is your website load? That is the question I’ve been asking these days. On my computer my website is load quite fast. But my question is how about other computers or visitors from other continents? Do they having the same browsing experience with me when they visit my website?
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Customizing Bash Prompt

I install several servers 2 days ago, what I found after I login to SSH is that the bash prompt is different with my older server, it only show “bash-3.1#” instead of “[username@servername – directory] $”

I found “bash-3.1#” is difficult as I don’t know my current directory location. With a little bit Google search I get an answer.

You can customize your bash prompt by creating a file named .bash_profile (there is a “dot” in front of the filename)

Insert this code in .bash_profile file:

export PS1="[u@h w]$ "

now your bash prompt will look like this:

[user@localhost /home/user]$

Creating Empty File with Specified Size

If you want to do some download speed test, you can create a dummy file which have specific file size. To create an empty file with size you want type this command:

dd if=/dev/zero of=10mb-file.bin bs=1024k count=10

The command above will create a 10 MB sized file. If you want to create another file with different size, change the number after “count=”. Any number given after “count=” will be multiplied by 1024k or 1MB.

Transferring Files from Remote Server to Remote Server Using SCP

If you have more than one server and want to transfer files between the two, you can use SCP (Secure Copy). Here is how to do it:

$ scp /folder/file-to-tranfer username@remote.host.net:/folder/file-destination-name

SCP then will ask the password for username on the remote host that already specified, insert the username and press enter. Wait until the transfer finished and your file will be copied to the destination server.
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Disable Shell Access

If you want to create a user on your server but doesn’t want to give him SSH access then you can run this command to disable his shell:

usermod -s /bin/false username

After running that command, the user specified will not have SSH access but still can do other things like FTP.

Failing RAID 1 HDD

Today I’m experiencing bad thing with RAID 1 HDD on one of RevTI servers. I’m ordering additional RAM for that server and got a very bad news from my administrator that the OS won’t boot after the RAM installed. DAMN!!

My admin said that the RAID causing problem which causes the OS didn’t load. He said that the system can’t recognize any OS inside the HDD, it’s just look like blank HDD.
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I’m Looking for Bluetooth Stereo Headset

I’m currently looking for a bluetooth stereo headset, here is my requirements for the bluetooth device:

• Behind-the-head neckband style
• Bluetooth v2.0
• Can be paired to 2 mobile phones (simultaneously)
• Can be paired to 1 PC and 1 mobile phone (simultaneously)
• Built-in microphone for phone call
• It should be wireless, only wire for charger allowed
• Price arround US$ 100

So far the most closes match with my requirements is Jabra BT620s. It have a good design and I like it. Problem is I don’t know where I can find it here in Jakarta.

Markus