Delete merged branches. (Stack Overflow)

git branch -D `git branch --merged | grep -v \* | xargs`

if you're having trouble linking a lib, run 'ld -llmpe --verbose', swapping out your lib name, and you'll see where ld is looking and not finding it.

ld -llmpe --verbose

If you take a photo on an iPhone, transfer the "photo" to your computer, end up with an AVI and want image files

ffmpeg -i IMG_1455.avi -r 1 -f image2 image-%3d.jpeg

If you are in the terminal while using an X Window system, and want to open a file or the current directory with the default application for it.

xdg-open .
xdg-open file

To search for identical files in the current directory and subdirectories

rdfind .

Get a quick year-month-day at the command line

$ echo $(date +%Y-%m-%d)
2020-05-22

If under Ubuntu 18.04 an NTFS partition is mounting read-only, run this command and re-mount to make it read/write

sudo ntfsfix /dev/sdb1

Pretty print python

python -m json.tool my_json.json

OS X simple timer

sleep $((5*60)); Say  "job complete"

Speed up a video 100x (link)

ffmpeg -i ppo-self-play-two-players.mov -filter:v "setpts=0.01*PTS" ppo-self-play-two-players-fast.mov

Simple web server on the command line

$ python -m http.server 8000
Serving HTTP on 0.0.0.0 port 8000 (http://0.0.0.0:8000/) ...

Check DNS settings on Mac OS X

scutil --dns