How to permanently disable Bluetooth on Ubuntu 17.04 Linux.
In the upper-left-hand corner of the screen, click the "Dash" icon and type "terminal". Click on the terminal icon.
Show the current version of Linux:
$ uname -a
Linux TC605 4.10.0-26-generic #30-Ubuntu SMP Tue Jun 27 09:30:12 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
In the terminal window, run the systemctl command. Note the Bluetooth service is enabled:
$ systemctl status bluetooth
● bluetooth.service - Bluetooth service
Loaded: loaded (/lib/systemd/system/bluetooth.service; enabled; vendor preset
Active: active (running) since Sat 2017-07-08 18:34:29 MDT; 35min ago
Docs: man:bluetoothd(8)
Main PID: 872 (bluetoothd)
Status: "Running"
Tasks: 1 (limit: 4915)
CGroup: /system.slice/bluetooth.service
└─872 /usr/lib/bluetooth/bluetoothd
Jul 08 18:34:29 TC605 bluetoothd[872]: Failed to obtain handles for "Service Cha
Jul 08 18:34:29 TC605 bluetoothd[872]: Sap driver initialization failed.
Jul 08 18:34:29 TC605 bluetoothd[872]: sap-server: Operation not permitted (1)
Jul 08 18:34:29 TC605 bluetoothd[872]: Failed to set mode: Blocked through rfkil
Jul 08 18:34:40 TC605 bluetoothd[872]: Endpoint registered: sender=:1.89 path=/M
Jul 08 18:34:40 TC605 bluetoothd[872]: Endpoint registered: sender=:1.89 path=/M
Jul 08 18:35:37 TC605 bluetoothd[872]: Endpoint unregistered: sender=:1.89 path=
Jul 08 18:35:37 TC605 bluetoothd[872]: Endpoint unregistered: sender=:1.89 path=
Jul 08 18:35:40 TC605 bluetoothd[872]: Endpoint registered: sender=:1.124 path=/
Jul 08 18:35:40 TC605 bluetoothd[872]: Endpoint registered: sender=:1.124 path=/
Stop the Bluetooth service:
$ sudo systemctl stop bluetooth.service
Permanently disable the Bluetooth service:
$ sudo systemctl disable bluetooth.service
Synchronizing state of bluetooth.service with SysV service script with /lib/systemd/systemd-sysv-install.
Executing: /lib/systemd/systemd-sysv-install disable bluetooth
Removed /etc/systemd/system/dbus-org.bluez.service.
$ systemctl status bluetooth
● bluetooth.service - Bluetooth service
Loaded: loaded (/lib/systemd/system/bluetooth.service; disabled; vendor prese
Active: inactive (dead)
Docs: man:bluetoothd(8)
Jul 08 19:27:53 TC605 bluetoothd[908]: Endpoint registered: sender=:1.85 path=/M
Jul 08 19:27:59 TC605 bluetoothd[908]: Endpoint unregistered: sender=:1.85 path=
Jul 08 19:27:59 TC605 bluetoothd[908]: Endpoint unregistered: sender=:1.85 path=
Jul 08 19:28:00 TC605 bluetoothd[908]: Endpoint registered: sender=:1.123 path=/
Jul 08 19:28:00 TC605 bluetoothd[908]: Endpoint registered: sender=:1.123 path=/
Jul 08 19:30:11 TC605 systemd[1]: Stopping Bluetooth service...
Jul 08 19:30:11 TC605 bluetoothd[908]: Terminating
Jul 08 19:30:11 TC605 bluetoothd[908]: Endpoint unregistered: sender=:1.123 path
Jul 08 19:30:11 TC605 bluetoothd[908]: Endpoint unregistered: sender=:1.123 path
Jul 08 19:30:11 TC605 systemd[1]: Stopped Bluetooth service.
Restart the machine to verify the Bluetooth service does not restart.
After the machine has been restarted, open a terminal window and check the Bluetooth service:
$ systemctl status bluetooth
● bluetooth.service - Bluetooth service
Loaded: loaded (/lib/systemd/system/bluetooth.service; disabled; vendor prese
Active: inactive (dead)
Docs: man:bluetoothd(8)
Saturday, July 08, 2017
Sunday, June 18, 2017
Move Ether From Coinbase Exchange To Local Exodus Wallet
If you want to buy bitcoin or ethereum on an exchange, US residents may consider Coinbase. Coinbase also trades litecoin, in addition to bitcoin and ethereum. For deposits, Coinbase accepts credit cards and checking accounts.
If you want to open an account with Coinbase, this link will give you an extra $10 to start your Coinbase account.
After you have purchased ether in your Coinbase account, you will want to install a wallet on a local machine in order to move the ether off the Coinbase exchange. After creating a local wallet, you will transfer the ether from Coinbase to the public key of your local wallet.
We will use the Exodus wallet, because it supports multiple coins. It also supports Shapeshift, to swap to different coins.
This example uses MS Windows 10 Pro, 64 bit.
Click here to download the Exodus wallet application. For this example, choose the Windows application.
Optionally scan the downloaded file for viruses.
Double-click the downloaded file to install Exodus. It will install and show a prompt telling you it has been installed. Look for the desktop shortcut and double-click it. This will display the main Exodus screen.
On the left side of the Exodus application, click Wallet.
Press Receive and the program will show your local ethereum address.
Press the left button to copy this address into the clipboard.
Login to Coinbase and go to Send/Request.
Paste the address from the clipboard, which was copied from the Exodus applictation, into the Recipient field of Coinbase.
Choose the amount to send, and select "ETH Wallet".
Press the Send Funds button.
Enter the authentication code, and confirm the transaction.
Coinbase will show the coin has been sent.
Go to the Exodus application and look for the received coin.
Exodus allows a backup to be created once there is any amount of coin in the wallet.Backup the wallet in Exodus by pressing the Backup button on the left side of the program.
Create a password.
The next Exodus screen will display twelve words. With these words, anyone can recreate the wallet. Print out or write down the twelve word password recovery words and keep the words private to yourself.
Enter an email address to receive a recovery link. Then log in to your email account and look for the email from support@exodus.io.
If you want to send a tip, use this ethereum public key address: 0xe3964791d573bf3459C8be9c1bffB35Ce4ddBC2e
If you want to open an account with Coinbase, this link will give you an extra $10 to start your Coinbase account.
After you have purchased ether in your Coinbase account, you will want to install a wallet on a local machine in order to move the ether off the Coinbase exchange. After creating a local wallet, you will transfer the ether from Coinbase to the public key of your local wallet.
We will use the Exodus wallet, because it supports multiple coins. It also supports Shapeshift, to swap to different coins.
This example uses MS Windows 10 Pro, 64 bit.
Click here to download the Exodus wallet application. For this example, choose the Windows application.
Optionally scan the downloaded file for viruses.
Double-click the downloaded file to install Exodus. It will install and show a prompt telling you it has been installed. Look for the desktop shortcut and double-click it. This will display the main Exodus screen.
On the left side of the Exodus application, click Wallet.
Press Receive and the program will show your local ethereum address.
Press the left button to copy this address into the clipboard.
Login to Coinbase and go to Send/Request.
Paste the address from the clipboard, which was copied from the Exodus applictation, into the Recipient field of Coinbase.
Choose the amount to send, and select "ETH Wallet".
Press the Send Funds button.
Enter the authentication code, and confirm the transaction.
Coinbase will show the coin has been sent.
Go to the Exodus application and look for the received coin.
Exodus allows a backup to be created once there is any amount of coin in the wallet.Backup the wallet in Exodus by pressing the Backup button on the left side of the program.
Create a password.
The next Exodus screen will display twelve words. With these words, anyone can recreate the wallet. Print out or write down the twelve word password recovery words and keep the words private to yourself.
Enter an email address to receive a recovery link. Then log in to your email account and look for the email from support@exodus.io.
If you want to send a tip, use this ethereum public key address: 0xe3964791d573bf3459C8be9c1bffB35Ce4ddBC2e
Wednesday, August 31, 2016
Bitcoin Reading List
Minimum Viable Block Chain, by Ilya Grigorik, is an introductory paper which includes most of the required concepts.
Bitcoin and Cryptocurrency Technologies was published from Princeton and has a corresponding Coursera course. The draft version of the book is available in a free pdf.
Financial services regulation and policy. Bitcoin A Primer For Policymakers is a free pdf.
Bitcoin and Cryptocurrency Technologies was published from Princeton and has a corresponding Coursera course. The draft version of the book is available in a free pdf.
Financial services regulation and policy. Bitcoin A Primer For Policymakers is a free pdf.
Mastering Bitcoin: Unlocking Digital Cryptocurrencies is a good read from O'Reilly.
Monday, June 27, 2016
SkypeHost.exe on Windows 10
Anyone who does not use Skype and who is looking through Task Manager may be frustrated to observe a task named SkypeHost.exe. While it may have "Suspended" status, some users would like to completely remove the task while not affecting Skype for other users on the PC.
SkypeHost.exe will restart if it is killed through "End task" in the Task Manager. The following instructions will remove the task, while allowing Skype to continue to function for other users of the PC.
The process is to open the Skype application and log in. Then choose "Options" and uncheck "Start Skype which I start Windows" and "Sign me in when Skype starts".
The process will end, and it will not restart the next time you log in.
SkypeHost.exe will restart if it is killed through "End task" in the Task Manager. The following instructions will remove the task, while allowing Skype to continue to function for other users of the PC.
The process is to open the Skype application and log in. Then choose "Options" and uncheck "Start Skype which I start Windows" and "Sign me in when Skype starts".
The process will end, and it will not restart the next time you log in.
Tuesday, June 07, 2016
Tuning I/O for Ethereum
At a high level, the I/O request goes from the running program to the operating system. Then from the operating system to the appropriate file system driver, then to the disk controller which writes to the disk.
It is usually important to match the I/O length (the amount of data being written) in each step of the process. Disks and the disk controllers typically write large stripes of data, such as 512KB. The file system may be set up with RAID, which can have stripes of 512KB or 1 MB. The operating system may default to a size of 16 KB (NTFS default has been 4 KB). To complicate this further, the operating system may implement file compression, which can pack more data into each I/O. And remember the filesystem may have logging, and may also frequently update inode access times which can cause contention.
It is typically difficult to change RAID settings after it has been implemented. RAID 5 will often be slow. It is typically impossible to change disk controller settings.
Therefore, let's concentrate on tuning a high I/O workload with commonly available settings in the filesystem and the program.
Increase the filesystem block size to a reasonably large value such as 64 KB. This is set when formatting a partition. While larger block sizes can lead to some wasted disk space, this is not typically a problem with modern large disks.
For tuning the program, if possible increase the program's (database or geth) cache size and match the logical I/O to the filesystem I/O size. For geth, it is possible to set the cache size with the --cache flag:
.\geth.exe --cache 512
The default geth cache is 16 MB, so 512 MB is a large increase. Set this lower than the amount of real RAM in the system, to avoid creating a swapping situation. Monitor this with Task Manager, using the following examples. Note 1.6 GB of real RAM is available to avoid swapping, which is a safe margin of error in case the program data increases.
Using the geth default of 16 MB, the maximum observed I/O was about 3 MB per second. Using geth's cache of 512 MB increased the maximum I/O to about 12 MB per second, a significant increase.
It is usually important to match the I/O length (the amount of data being written) in each step of the process. Disks and the disk controllers typically write large stripes of data, such as 512KB. The file system may be set up with RAID, which can have stripes of 512KB or 1 MB. The operating system may default to a size of 16 KB (NTFS default has been 4 KB). To complicate this further, the operating system may implement file compression, which can pack more data into each I/O. And remember the filesystem may have logging, and may also frequently update inode access times which can cause contention.
It is typically difficult to change RAID settings after it has been implemented. RAID 5 will often be slow. It is typically impossible to change disk controller settings.
Therefore, let's concentrate on tuning a high I/O workload with commonly available settings in the filesystem and the program.
Increase the filesystem block size to a reasonably large value such as 64 KB. This is set when formatting a partition. While larger block sizes can lead to some wasted disk space, this is not typically a problem with modern large disks.
For tuning the program, if possible increase the program's (database or geth) cache size and match the logical I/O to the filesystem I/O size. For geth, it is possible to set the cache size with the --cache flag:
.\geth.exe --cache 512
The default geth cache is 16 MB, so 512 MB is a large increase. Set this lower than the amount of real RAM in the system, to avoid creating a swapping situation. Monitor this with Task Manager, using the following examples. Note 1.6 GB of real RAM is available to avoid swapping, which is a safe margin of error in case the program data increases.
Using the geth default of 16 MB, the maximum observed I/O was about 3 MB per second. Using geth's cache of 512 MB increased the maximum I/O to about 12 MB per second, a significant increase.
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