* How to Boot ISO Images Directly From your Hard Disk Drive?
** Download ISO of your favourite distro!
*** Download Ubuntu ISO
      https://ubuntu.com/download
*** Download Linux Mint ISO
      https://www.linuxmint.com/download.php

*** Download Pop OS ISO
      https://pop.system76.com/

*** Download Elementary OS ISO
      https://elementary.io/

*** Download Fedora OS ISO
      https://getfedora.org/en/workstation/download/

*** Download Zorin OS ISO
      https://zorin.com/os/download/
      
** Modify File '/etc/default/grub'

  =sudo nano /etc/default/grub=

#+begin_src shell
  # Change this line:

  GRUB_TIMEOUT_STYLE=menu
  GRUB_TIMEOUT=10
  #Save and exit
#+end_src

*** Update GRUB
   =sudo update-grub= 

** Create the GRUB Boot entry
*** create live directory
       =mkdir /live=
*** copy all iso files to the directory
       =cp *.iso /live=

*** Add boot entry to file /etc/grub.d/40_custom
       =sudo gedit /etc/grub.d/40_custom=

*** Copy this code to 40_custom file

#+begin_src shell

  #!/bin/sh
  exec tail -n +3 $0
  # This file provides an easy way to add custom menu entries.  Simply type the
  # menu entries you want to add after this comment.  Be careful not to change
  # the 'exec tail' line above.
  menuentry "Ubuntu 21.04 Live"{
      set isofile="/live/ubuntu-20.04.3-desktop-amd64.iso"
      loopback loop (hd0,msdos5)$isofile
      linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=${isofile} quiet splash
      initrd (loop)/casper/initrd
  }
  menuentry "Fedora 35 Live"{
      insmod ext2
      set isofile="/live/Fedora-Workstation-Live-x86_64-35_Beta-1.2.iso"
      loopback loop (hd0,msdos5)$isofile
      linux (loop)/isolinux/vmlinuz root=live:CDLABEL=Fedora-WS-Live-35_B-1-2 rd.live.image verbose iso-scan/filename=$isofile
      initrd (loop)/isolinux/initrd.img
  }
  menuentry "Kali Linux 2021 Live"{
      insmod ext2
      set isofile="/live/kali-linux-2021.3-live-amd64.iso"
      loopback loop (hd0,msdos5)$isofile
      linux (loop)/live/vmlinuz boot=live findiso=$isofile
      initrd (loop)/live/initrd.img
  }
  menuentry "Linux Mint 20.2 Live"{
      set isofile="/live/linuxmint-20.2-cinnamon-64bit.iso"
      loopback loop (hd0,msdos5)$isofile
      linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=${isofile} quiet splash
      initrd (loop)/casper/initrd.lz
  }
  menuentry "Manjaro Live"{
      set isofile="/live/manjaro-gnome-20.2.1-210103-linux59.iso"
      search --no-floppy -f --set=root $isofile
      probe -u $root --set=abc
      set pqr="/dev/disk/by-uuid/$abc"
      loopback loop $isofile
      linux  (loop)/boot/vmlinuz-x86_64  img_dev=$pqr img_loop=$isofile copytoram
      initrd  (loop)/boot/intel_ucode.img (loop)/boot/initramfs-x86_64.img
  }
  menuentry "MX Linux 21 Live"{
      set isofile="/live/MX-21_KDE_RC1_x64.iso"
      search --no-floppy --set=root --file $isofile
      probe -u $root --set=buuid
      loopback loop $isofile
      set root=(loop)
      linux  /antiX/vmlinuz buuid=$buuid fromiso=$isofile quiet 
      initrd /antiX/initrd.gz
  }

#+end_src

*** Update the grub
   =sudo update grub=

** Reboot AND Enjoy!
* Hexadecimal colo codes for transparency
** How to set transparency with hex value?
For example, you want to set 40% alpha transparence to #000000 (black color), you need to add 66 like this #00000066.

** All hex value from 100% to 0% alpha:
#+begin_src conf 

    100% — FF
    99% — FC
    98% — FA
    97% — F7
    96% — F5
    95% — F2
    94% — F0
    93% — ED
    92% — EB
    91% — E8
    90% — E6
    89% — E3
    88% — E0
    87% — DE
    86% — DB
    85% — D9
    84% — D6
    83% — D4
    82% — D1
    81% — CF
    80% — CC
    79% — C9
    78% — C7
    77% — C4
    76% — C2
    75% — BF
    74% — BD
    73% — BA
    72% — B8
    71% — B5
    70% — B3
    69% — B0
    68% — AD
    67% — AB
    66% — A8
    65% — A6
    64% — A3
    63% — A1
    62% — 9E
    61% — 9C
    60% — 99
    59% — 96
    58% — 94
    57% — 91
    56% — 8F
    55% — 8C
    54% — 8A
    53% — 87
    52% — 85
    51% — 82
    50% — 80
    49% — 7D
    48% — 7A
    47% — 78
    46% — 75
    45% — 73
    44% — 70
    43% — 6E
    42% — 6B
    41% — 69
    40% — 66
    39% — 63
    38% — 61
    37% — 5E
    36% — 5C
    35% — 59
    34% — 57
    33% — 54
    32% — 52
    31% — 4F
    30% — 4D
    29% — 4A
    28% — 47
    27% — 45
    26% — 42
    25% — 40
    24% — 3D
    23% — 3B
    22% — 38
    21% — 36
    20% — 33
    19% — 30
    18% — 2E
    17% — 2B
    16% — 29
    15% — 26
    14% — 24
    13% — 21
    12% — 1F
    11% — 1C
    10% — 1A
    9% — 17
    8% — 14
    7% — 12
    6% — 0F
    5% — 0D
    4% — 0A
    3% — 08
    2% — 05
    1% — 03
    0% — 00
#+end_src