Run a TFTP Server on Mac OS X

To upgrade firmware or upload config backup on networking devices TFTP server often comes handy. In my job I usually have access tosuch server, but in some cases when network access is limited or not available I configure a TFTP server on my laptop. For Linux see: Install and run a TFTP server

Mac OS X has a tftp server included, it's eazy to start it and do a minor configuration. First see if there are any commands related to tftp.

apropos tftp

You should get answer like this.

tftp(1) - trivial file transfer program
tftpd(8) - DARPA Internet Trivial File Transfer Pro

You can start it with launchctl

sudo launchctl load -F /System/Library/LaunchDaemons/tftp.plist

To confirm it’s running use netstat to check what is listening on its port, traditionally port 69.

netstat -na |grep \*.69

Should get answer like this.

udp6       0      0  *.69                   *.*
udp4       0      0  *.69                   *.*

It's a good idea to symlink the tftpboot to a folder you have full control over because OS X El Capitan has strong security via its System Integrity Protection (SIP) which makes things more difficult.

cd /private/
sudo rm -rf tftpboot
mkdir /Users/<username>/tftpboot
sudo ln -s /Users/<username>/tftpboot tftpboot
sudo launchctl unload -F /System/Library/LaunchDaemons/tftp.plist
sudo launchctl load -F /System/Library/LaunchDaemons/tftp.plist

When you’re not using the TFTP server, make sure to unload the service.

sudo launchctl unload -F /System/Library/LaunchDaemons/tftp.plist
netstat -na |grep \*.69

The netstat should return nothing.

-cheers

Restoring a single table from a full mysqldump file

Yesterday I needed to restore one table from larger database dump file. To begin with I found out which lines I needed end with sed i got my data.

sed -n 955,991p data.sql > new_data.sql

Pretty easy, but in a large file you have to work your way to find the line you need. The solution I found was more specific and works like a charm. The first version of the command was a rather inaccurate because it was missing the "DROP TABLE IF EXIST" for the table you are restoring and you need to edit out few lines from the bottom of the new file before using it in order to prevent deleting the next table, "address". leaves "DROP TABLE IF EXIST" for the next table at the end of the new file.

sed -n -e '/CREATE TABLE.*`person`/,/CREATE TABLE/p' data.sql > new_data.sql

Leves this at the end og the new file.

--
-- Table structure for table `address`
--

DROP TABLE IF EXISTS `address`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `address` (

Then I came a cross better solution to get your table data. While this is the backup layout.

--
-- Table structure for table `person`
--

DROP TABLE IF EXISTS `person `;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `person` (
  `id` int(4) NOT NULL AUTO_INCREMENT,
  `name` varchar(225) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;
/*!40101 SET character_set_client = @saved_cs_client */;

--
-- Dumping data for table `person`
--

LOCK TABLES `person` WRITE;
/*!40000 ALTER TABLE `person` DISABLE KEYS */;
INSERT INTO `person` VALUES (1,'Emma'),(2,'Noah'),(3,'Olivia'),(4,'Liam'),(5,'Sophia');
/*!40000 ALTER TABLE `person` ENABLE KEYS */;
UNLOCK TABLES;

As you can see "UNLOCK TABLES" is the last line, so that is what we look for in the sed ccommand.

sed -n -e '/DROP TABLE IF EXISTS.*`person`/,/UNLOCK TABLES/p' data.sql > new_data.sql

Now your new file should be ready to use, but I recommend that you check before you use.

--cheers

How to disable the Caps Lock key on Mac

Caps Lock is the the most unnecessary key on the keyboard for me. I rarely need to write more than couple of words in capitals and to often I accidently hit the key, suddenly finding myself typing IN ALL CAPS
Here’s an easy way to change the behavior of your Mac’s Caps Lock key and even disable it altogether.

• Click the  icon in the top-left corner of your desktop and select System Preferences
• Select the Keyboard icon and click the “Modifier Keys” button in the bottom-right corner 
• From the pull-down menu next to “Caps Lock Key”, select “No Action” 
• Press “OK”

See also: How to disable the Caps Lock key on Ubuntu

How you can make someone unfollow you on Twitter

This trick is known as a "soft block", and it comes handy when someone’s annoying you on Twitter and you really do not want to block him. You have a few options for dealing with annoying accounts.
Block, which prevents them seeing your tweets.
Mute, which stops you seeing their tweets and replies to you.
And Soft block which forces them to unfollow you.
If you are active Twitter user you are most likely familiar to Block and Mute. But you might or might not have heard about Soft block. Because It’s not an official feature, soft block is not commonly known.
The procedure is quite simple, all you have to do is promptly block and unblock the user in question.

If the person doesn’t notice you’re not coming up in their feed anymore, you’re good. Else repeat.

--Cheers

Restoring applications after minimizing to Mac OS X dock

When you click the yellow pill button in the upper left corner of a window to minimize that window in Mac OS X or if you use ⌘ Cmd + M you might want to bring the application back. When cycling through running applications, including the minimised applications, using ⌘ Cmd + Tab you might expect to retrieve the application back.

This sequence on the other hand will bring wour application window.
1. Use ⌘ Cmd + Tab untill you find your application.
2. Before releasing ⌘ Cmd, press and hold ⌥ Alt

Other method is to hide application using ⌘ Cmd + H, then you can restore your window with ⌘ Cmd + Tab

Using Python, MySQL and UTF-8

I have been spending way to long time figuring out how I can encode my data to utf8 when fetching records from MySQL database. All the time I was focusing on encoding the output, resulting in error like this one.

UnicodeDecodeError: 'ascii' codec can't decode byte 0xe1 in position 1: 
ordinal not in range(128)

The solution I finally found is to set the character set when I prepare the MySQL connection

con.set_character_set('utf8')

Ending up in my code like this.

!/usr/bin/env python
# -*- coding: utf-8 -*-
import MySQLdb as mdb

def getname(p):
    con = mdb.connect('hostname', 'username', ' password', 'databasname')
    con.set_character_set('utf8')
    sql = "SELECT cellname1 from tablename where cellname2='%s'"%(str(p))
    cur = con.cursor()
    cur.execute(sql)
    row = cur.fetchone()
    if not row:
        return 'n/a'
    else:
        return str(row[0])
    cur.close()

Now everything works like a charm.