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Table of Contents

• set -e, -u, -x, -o pipefail
• set -e
• set -x
• set -u
• set -o pipefail
• Setting IFS
• Original Reference

set -e, -u, -x, -o pipefail

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Git cheatsheet

Find all instances of text in all commits

git grep "text to look for" $(git rev-list --all)

List commit messages since given commit

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Pages

• Which Version of JDK Should I Use? - whichjdk.com
• JDK Distributions - sdkman.io/jdks
• https://jdk.dev

Distributions

• OpenJDK builds by Oracle (jdk.java.net)
• Oracle Java SE Development Kit (JDK)

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Moving efficiently in the CLI

Copied from: Moving efficiently in the CLI

Github: clementC/my_blog/content/figures/moving_cli.png

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Capture a video of a given X Window with gstreamer.

X Window ID

Get the target window ID with the following:

xwininfo

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#!/bin/bash
# =========================================================================
# Source: https://gist.github.com/lucaspar/27f5e108b80524b315be10b2a9049817
# =========================================================================
# This script will compile and install a static FFmpeg build with
#   support for NVENC in Ubuntu. Developed in Ubuntu 23.10,
#   with NVIDIA Drivers v535.129.03 and CUDA v12.2 with a GPU
#   with CUDA capability 8.6 (RTX 3080) (see ccap below).
# It assumes NVIDA drivers are installed and that you have a
#   CUDA-compatible GPU. You can check installed drivers with:

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# https://wiki.archlinux.org/title/NVIDIA/Tips_and_tricks
# https://forums.developer.nvidia.com/t/does-modprobe-d-nvidia-conf-nvreg-enablestreammemops-need-to-be-set-for-gpudirect-to-work/79511
# https://github.com/NVIDIA/open-gpu-kernel-modules/blob/main/src/nvidia/interface/nvrm_registry.h
# Requires nvidia.ko >= 510.40.3 loaded with PeerMappingOverride=1. https://docs.nvidia.com/nvshmem/install-guide/index.html
# https://wiki.gentoo.org/wiki/NVIDIA/nvidia-drivers/en
# https://github.com/ventureoo/nvidia-tweaks
# https://nvdam.widen.net/s/k8vrp9xkft/tech-overview-magnum-io-1790750-r5-web
# https://developer.download.nvidia.com/devzone/devcenter/cuda/docs/GPUDirect_Technology_Overview.pdf
# https://docs.nvidia.com/nvshmem/pdf/NVSHMEM-Installation-Guide.pdf

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#!/usr/bin/env bash

# 1. Download and install the QEMU hook helper from here: https://github.com/PassthroughPOST/VFIO-Tools
# 2. Place this file in /etc/libvirt/hooks/qemu.d/NAME OF YOUR VM/prepare/begin/disable-fb.sh
# 3. Make disable-fb.sh executable.

VM_NAME="$1"
echo "libvirt-qemu disable-fb: Disabling efi-framebuffer to prepare to pass GPU to VM $VM_NAME" > /dev/kmsg 2>&1
echo "efi-framebuffer.0" > /sys/bus/platform/devices/efi-framebuffer.0/driver/unbind

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Encoding high-quality HEVC content in a two-pass manner with FFmpeg - based NVENC encoder on supported hardware:

If you've built ffmpeg as instructed here on Linux and the ffmpeg binary is in your path, you can do fast HEVC encodes as shown below, using NVIDIA's NPP's libraries to vastly speed up the process.

Now, to do a simple NVENC encode in 1080p, (that will even work for Maxwell Gen 2 (GM200x) series), start with:

ffmpeg  -i <inputfile> -pass 1 \
-filter:v hwupload_cuda,scale_npp=w=1920:h=1080:format=nv12:interp_algo=lanczos,hwdownload,format=nv12 \

-c:v hevc_nvenc -profile main -preset slow -rc vbr_2pass \

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Because PowerMizer settings in NVIDIA X Server Settings doesn't persist across sessions, 
attempts to overclock can become a nuisance.

The following documents the three CLI settings to modify the Preferred Mode as desired:

# Auto:
nvidia-settings -a [gpu:0]/GPUPowerMizerMode=2

# Adaptive:
nvidia-settings -a [gpu:0]/GPUPowerMizerMode=0