Gliding Phenomena

Azure VM --os-disk-size-gb partition, format and mount

If you are using Azure VM --os-disk-size-gb parameter to increase the size of the OS disk, you need to partition, format and mount to use it.

Check the current status with

 fdisk -l

 df -Th 

Step 1: Create a partition (See sample output below)

 sudo fdisk /dev/sda

(use n to create new partition, and follow prompts)

Step 2: Refresh partition table
sudo partprobe

Step 3: Format the new partition, get the name from step 1 or use fdisk -l

 mkfs.xfs /dev/sda3 

Step 4: Mount

 mkdir /mnt/shared

 mount /dev/sda3 /mnt/shared/  

Step 5: Verify

 df -Th 

Step 6: Edit the /etc/fstab to automatically mount when restarted

 vi  /etc/fstab

Append line /dev/sda3 /mnt/shared xfs defaults 0 0 . Please note the filesystem type "xfs" is used as it was formatted in "xfs" in Step 3. You could use other formats as well based on your requirements .

#

# /etc/fstab                                                                                                                   

# Created by anaconda on Wed Dec 19 23:06:16 2018                                                                              

#

# Accessible filesystems, by reference, are maintained under '/dev/disk'                                                       

# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info                                                    

#

UUID=fdb125e2-1ce5-4b7a-98db-88c0f66a86ee /                       xfs     defaults        0 0                                  

UUID=d4c5a046-3513-4ff0-a955-621311869210 /boot                   xfs     defaults        0 0                                  

/dev/sda3 /mnt/shared xfs defaults 0 0     

Sample Output:

[root@azvm azureusr]# fdisk /dev/sda

The device presents a logical sector size that is smaller than

the physical sector size. Aligning to a physical sector (or optimal

I/O) size boundary is recommended, or performance may be impacted.

Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.

Be careful before using the write command.

Command (m for help): n

Partition type:

   p   primary (2 primary, 0 extended, 2 free)

   e   extended

Select (default p): 

Using default response p

Partition number (3,4, default 3): 

First sector (62914560-125829119, default 62914560): 

Using default value 62914560

Last sector, +sectors or +size{K,M,G} (62914560-125829119, default 125829119): 

Using default value 125829119

Partition 3 of type Linux and of size 30 GiB is set

Command (m for help): w

The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.

The kernel still uses the old table. The new table will be used at

the next reboot or after you run partprobe(8) or kpartx(8)

Syncing disks.

[root@azvm azureusr]# partprobe

[root@azvm azureusr]# fdisk -l

Disk /dev/sda: 64.4 GB, 64424509440 bytes, 125829120 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 4096 bytes

I/O size (minimum/optimal): 4096 bytes / 4096 bytes

Disk label type: dos

Disk identifier: 0x000eba6a

   Device Boot      Start         End      Blocks   Id  System

/dev/sda1   *        2048     1026047      512000   83  Linux

/dev/sda2         1026048    62914559    30944256   83  Linux

/dev/sda3        62914560   125829119    31457280   83  Linux

Disk /dev/sdb: 751.6 GB, 751619276800 bytes, 1468006400 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 4096 bytes

I/O size (minimum/optimal): 4096 bytes / 4096 bytes

Disk label type: dos

Disk identifier: 0x3fde6d89

   Device Boot      Start         End      Blocks   Id  System

/dev/sdb1             128  1468004351   734002112   83  Linux

[root@azvm azureusr]# df -Th

Filesystem     Type      Size  Used Avail Use% Mounted on

/dev/sda2      xfs        32G  5.8G   26G  19% /

devtmpfs       devtmpfs  186G     0  186G   0% /dev

tmpfs          tmpfs     186G     0  186G   0% /dev/shm

tmpfs          tmpfs     186G  9.5M  186G   1% /run

tmpfs          tmpfs     186G     0  186G   0% /sys/fs/cgroup

/dev/sda1      xfs       521M   68M  454M  13% /boot

/dev/sdb1      ext4      740G   76M  703G   1% /mnt/resource

tmpfs          tmpfs      38G     0   38G   0% /run/user/1000

[root@azvm azureusr]# mkfs.xfs /dev/sda3 

meta-data=/dev/sda3              isize=512    agcount=4, agsize=1966080 blks

         =                       sectsz=4096  attr=2, projid32bit=1

         =                       crc=1        finobt=0, sparse=0

data     =                       bsize=4096   blocks=7864320, imaxpct=25

         =                       sunit=0      swidth=0 blks

naming   =version 2              bsize=4096   ascii-ci=0 ftype=1

log      =internal log           bsize=4096   blocks=3840, version=2

         =                       sectsz=4096  sunit=1 blks, lazy-count=1

realtime =none                   extsz=4096   blocks=0, rtextents=0

[root@azvm azureusr]# mkdir /mnt/shared

[root@azvm azureusr]# mount /dev/sda3 /mnt/shared/ 

[root@azvm azureusr]# df -Th

Filesystem     Type      Size  Used Avail Use% Mounted on

/dev/sda2      xfs        30G  5.4G   25G  19% /

devtmpfs       devtmpfs  174G     0  174G   0% /dev

tmpfs          tmpfs     174G     0  174G   0% /dev/shm

tmpfs          tmpfs     174G  9.1M  174G   1% /run

tmpfs          tmpfs     174G     0  174G   0% /sys/fs/cgroup

/dev/sda1      xfs       497M   65M  433M  13% /boot

/dev/sdb1      ext4      689G   73M  654G   1% /mnt/resource

tmpfs          tmpfs      35G     0   35G   0% /run/user/1000

/dev/sda3      xfs        30G   33M   30G   1% /mnt/shared

Get Memory information in Linux


sudo dmidecode --type 17

Watch CPU Frequencies in real time


sudo watch -n 1  cat /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_cur_freq

Unblock a specific port from the firewall in Centos 7

Following is a example which unblocks port 8888


firewall-cmd --permanent --add-port=8888/tcp
firewall-cmd --reload
firewall-cmd --list-all

opencv: Install opencv CentOS


sudo yum install opencv opencv-python opencv-devel-docs 

#OPTIONAL DEPENDENCIES:
sudo yum install -y python-devel gtk2-devel libdc1394-devel libv4l-devel ffmpeg-devel gstreamer-plugins-base-devel
sudo yum install -y libpng-devel libjpeg-turbo-devel jasper-devel openexr-devel libtiff-devel libwebp-devel
sudo yum install -y gcc  cmake  git gtk2-devel pkgconfig  numpy  ffmpeg

If your using virtual environment, copy the relevant cv files to the virtual environment.


 cp /usr/lib64/python2.7/site-packages/cv* .venv/lib/python2.7/site-packages/

Caffe: Visualizing Caffe Network prototxt file using GraphViz: draw_net.py

Visualizing Caffe Net topology/ntwork/prototxt file using GraphViz
From the Caffe root directory, you can generate a graph in image format from a .prototxt model file:


#INSTALL PRE-REQS:
$ make pycaffe
$ pip install pydotplus
$ yum install graphviz

Visualize a CNN in left-to-right:


#goto CAFFE ROOT
$ python/draw_net.py mynetwrk.prototxt mynetwrk.png

Output formats could be : PNG, PDF, DOT or other GraphViz supported formats.
Visualize a CNN in top-to-bottom:


$ python/draw_net.py --rankdir TB mynetwrk.prototxt mynetwrk.png

Following errors can be eliminated if you install the PRE-REQS (pip install pydotplus; yum install graphviz)


pydotplus.graphviz.InvocationException: GraphViz's executables not found
Exception: "dot" not found in path.
ImportError: No module named pydot

Github: Merging two branches


git remote add remote-name remote-github-url 
git fetch remote-name 
git merge remote-name/branch-name 
git status

Github: Update a GitHub forked repository;


git remote add upstream github-URL
git fetch upstream 
git merge upstream/master master 
git pull upstream master 
git push

Sublime Text: Multiple cursors or Multi-selection

Multiple cursors or Multi-selection in sublime text is easy

Press Alt/Command and then click in each region where you require a cursor.
Select a block of lines : Shift + Command + L.
Place the cursor over a particular word, and press Control/Command + D repeatedly to select additional occurrences of that word.
Add an additional cursor at all occurrences of a word : Alt+F3 on Windows or Ctrl+Command+G on Mac.

Laravel: Debug by Printing Eloquent Query

Use ->toSql() method like shown below to get the SQL


<?php
use Log;

$name = "hawk";

$userResults = DB::table('users')
       ->leftJoin('planets', function($join) {
         $join->on('users.planet_id', '=' , 'planets.id');
        })
       ->where('users.lname' , 'like', '%'.$name.'%');

//You can print the SQL in your log file
Log::info('My search sql: '.($userResults->toSql()));

// OR you can save into a string variable
$mySQL = $userResults->toSql();

//Then use your get function
$userResults = $userResults->get(array('users.fname', 'planets.name'));
?>

The above code will print the following into your /storage/logs/laravel.log file


[2014-09-30 17:58:07] production.INFO: My search sql: SELECT * FROM  users LEFT JOIN planets ON (users.planet_id = planets.id) WHERE users.lname LIKE '%hawk%'

Laravel 4: Easy Installation of PHP mcrypt extension for OS X 10.8/10.9

An automated PHP mcrypt extension installer for OS X 10.8/10.9 - Mountain lion and Mavericks.

Download here: http://topicdesk.com/downloads/mcrypt/mcrypt-download

Laravel, Eloquent: SQL query with left join

If the query needs parentheses/brackets for a where condition like below Normal SQL:


SELECT users.fname, planets.name 
FROM  users
LEFT JOIN  planets ON (users.planet_id = planets.id)
WHERE users.lname LIKE '%hawk%'

ELOQUENT SQL:


$name = "hawk";

$userResults = DB::table('users')
       ->leftJoin('planets', function($join) {
         $join->on('users.planet_id', '=' , 'planets.id');
        })
       ->where('users.lname' , 'like', '%'.$name.'%')
       ->get(array('users.fname', 'planets.name'));

Eloquent: SQL Query with where or in brackets

If the query needs parentheses/brackets for a where condition like below Normal SQL:


SELECT * 
FROM  users
WHERE planet = 'earth'
AND (fname LIKE '%hawk%' OR lname LIKE '%hawk%')
AND state = 'FL'

ELOQUENT SQL:


$name = "hawk";

$usersResults = DB::table('users')
    ->where('planet', '=', 'earth')
    ->where(function($query) use ($name){
            $query->where('fname' , 'like', '%'.$name.'%');
            $query->orWhere('lname' , 'like', '%'.$name.'%');
      })
     ->where('state', '=', 'FL')
    ->get();

Wordpress: Print-friendly, Print as it looks in browser

If you you want to print a wordpress blog/site as it looks on the browser, then you have to
1. Login to the Wordpress as admin
2. Goto Appearance->Editor in the Left Sidebar menu.
3. On the right side find Header.php file
4. In the file locate the following piece of code


<link rel=”stylesheet” href=”<?php bloginfo(‘stylesheet_url’); ?>” type=”text/css” media=”screen” />

5. Modify to the media=""screen" to media="screen, print"
6. Click Update file at the bottom to save the changes in header.php


<link rel=”stylesheet” href=”<?php bloginfo(‘stylesheet_url’); ?>” type=”text/css” media=”screen, print” />

Oracle: Split a String Based on Delimiter

We can split a string based on Delimiter using a combination of INSTR and SUBSTR functions:

INSTR Returns the position of a String within a String. For more information see Oracle instr function
SUBSTR Returns a substring. For more information see Oracle substring
Syntax of SUBSTR:


SUBSTR([input],[start],[length])

Example 1:

 
select substr('orange.apple',1,(instr('orange.apple','.')) - 1)  
 from  dual

Output:
first

Example 2:

 
select substr('orange.apple',1,(instr('orange.apple,'.')) - 1) as First,  
        substr('orange.apple', (instr('orange.apple','.')) + 1) as Second  
 from  dual

Output:
First Second
orange apple