Gliding Phenomena

Connecting to Ubuntu Remote Desktop from Mac OS

Connecting to Ubuntu or any linux server via Mac OS:
-- Access the "Spotlight" by hitting CMD + Space-bar
-- Within the Spotlight field, enter vnc://your_server_ip:5900

If you get an error when connecting to Ubuntu from Mac OS using VNC screen sharing:
"The software on the remote computer appears to be incompatible with this version of Screen Sharing."
On Ubuntu 18.04:

$ gsettings set org.gnome.Vino require-encryption false

Verify the setting with

$ gsettings list-recursively org.gnome.Vino | grep encrypt

Fix wrong time in Ubuntu

Fix wrong time in Ubuntu .

sudo timedatectl set-local-rtc 1 --adjust-system-clock

BIOS settings to Install Ubuntu

If Ubuntu installation shows only the USB drive from which you are installing, make sure you have the BIOS settings as follows.

BIOS settings to Install Ubuntu alongside with Windows :

Disable Secure Boot.
Set SATA-controller to AHCI from RAID On.
Set boot mode to legacy from UEFI.

How to fix error Requires: libva.so.1(VA_API_0.33.0)(64bit)

If you get the following error while installing FFMPEG or other packages on CentOS 7.


Requires: libva.so.1(VA_API_0.33.0)(64bit)

Follow the following steps to install libva


sudo yum install libwayland-client    

wget http://mirror.centos.org/centos/7/os/x86_64/Packages/libva-1.8.3-1.el7.x86_64.rpm 

sudo rpm -i libva-1.8.3-1.el7.x86_64.rpm

Sample error log when installing FFMPEG:


Error: Package: ffmpeg-libs-3.4.7-1.el7.x86_64 (rpmfusion-free-updates)
           Requires: libva.so.1(VA_API_0.33.0)(64bit)
Error: Package: ffmpeg-libs-3.4.7-1.el7.x86_64 (rpmfusion-free-updates)
           Requires: libva-x11.so.1()(64bit)
Error: Package: libmfx-1.21-2.el7.x86_64 (epel)
           Requires: libva-x11.so.1()(64bit)
Error: Package: libmfx-1.21-2.el7.x86_64 (epel)
           Requires: libva-drm.so.1()(64bit)
Error: Package: ffmpeg-libs-3.4.7-1.el7.x86_64 (rpmfusion-free-updates)
           Requires: libva-drm.so.1()(64bit)
Error: Package: ffmpeg-libs-3.4.7-1.el7.x86_64 (rpmfusion-free-updates)
           Requires: libva.so.1()(64bit)
Error: Package: libmfx-1.21-2.el7.x86_64 (epel)
           Requires: libva.so.1()(64bit)

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