Host OS: Ubuntu 16.04+(recommended) or BBQ LINUX

## BBQ LINUX users can skip these package installations, just update it by -> sudo pacman -Suy <-
# Required packages
sudo apt-get install bison build-essential g++-multilib git make python zip
# JDK
sudo apt-get install openjdk-8-jdk # Ubuntu 16.04+
or
sudo apt-get install openjdk-7-jdk # Ubuntu 14.04

Create twrp dir:

 mkdir ~/twrp && cd ~/twrp

Recommended version: omni_twrp_5.1_cleaned

Other versions: TWRP Source releases

Get the right version of the source i.e. don't try higher version then your stock ROM unless you're using a custom kernel which supports the latest source.

# Download the desired source (for ex: 5.1_norepo)
aria2c -x16 -s16 URL
# Extract the source:
tar -xvf omni_twrp-5.1.1_cleaned.tar.xz --directory ~/twrp/

git clone https://github.com/TwrpBuilder/android_device_generic_twrpbuilder.git ~/twrp/device/generic/twrpbuilder

git clone https://github.com/omnirom/android_bootable_recovery.git ~/twrp/bootable/recovery --depth=1

Download the latest TWRP-Tree-Generator and save it in ~/twrp/

Put any working recovery.img in ~/twrp/

Make the device tree:

java -jar TwrpBuilder-1.0-SNAPSHOT.jar -r recovery.img

Output be like this:

Building tree using: recovery.img
Found gzip comression in ramdisk
Making "omni_q417".mk
Making Android.mk
Making AndroidProducts.mk
Making kernel.mk
Generating fstab
/data ext4 /dev/block/mmcblk0p3
/system ext4 /dev/block/mmcblk0p6
/cache ext4 /dev/block/mmcblk0p2
found mt6735 platform
Found 64 bit arch
Build fingerPrint: Micromax/Q417/Q417:5.1/LMY47D/1446202623:user/release-keys
tree ready for q417 at `device/micromax/q417`
Warning :- Check recovery fstab before build

Note down the "omni_q417" as it is needed for lunch ;)

Verify `device/micromax/q417/recovery.fstab` for mount points

. build/envsetup.sh
lunch "omni_q417"-eng    #device code from previous step(without quotes)
make -j4 recoveryimage

Make sure you've openjdk not oraclejdk

For GCC 7.x (Ubuntu 17.10+):

export LC_ALL=C

also in file external/sepolicy/tools/check_seapp.c add __attribute__((fallthrough)); above line: 740

 735:		else {
 736:	  		log_error(
 737:				"Unknown option character `\\x%x'.\n",
 738:				optopt);
 739: 		}
 740:		__attribute__((fallthrough));
 741:	default:
 742:		exit(EXIT_FAILURE);
 743:	}

If you're facing error related to fstab.goldfish, like this:

make: *** No rule to make target 'device/generic/goldfish/fstab.goldfish', needed by ..... Stop.

Clone device/generic/goldfish repo with the same version as the twrp source. For instance, if you're using 5.1 sources, use:

git clone https://android.googlesource.com/device/generic/goldfish -b android-5.1.1_r28 device/generic/goldfish