To Play a Random Video

mplayer -fs "$(ls | shuf -n1)"

To move the five most recent files to a subdirectory

ls -rt will show you the files most recent first.

To move the most recent five to a subdirectory:

mkdir -p recent && find -maxdepth 1 -type f -printf '%T@ %P\n' | sort -rn | cut -d' ' -f2- | head -n 5 | xargs -I{} mv {} recent

To Find the Most Recent Version of a File

Occasionally it so happens that you want to find the most recent version of thing.

Suppose that you're trying to find your most recent timesheet.

Then:

find ~ -type f -name "*timesheet*" -printf "%T@ %t %p\n" | sort -n 

does the business.

Output looks something like:

1519655146.5096155360 Mon Feb 26 14:25:46.5096155360 2018 /home/john/data/.~/timesheet.py.~86~
1519925511.1565392570 Thu Mar  1 17:31:51.1565392570 2018 /home/john/data/.~/timesheet.py.~87~
1520000595.5182763930 Fri Mar  2 14:23:15.5182763930 2018 /home/john/data/timesheet.py

Where the first column is a sortable version of the last modification time "%T@", and the second "%t" is the human readable form.

The last thing printed will be the most recent file in your home directory tree with timesheet in the name.

Linux Laptop Battery Level

sudo apt-get install acpi 
acpi -V

or:

upower -i `upower -e | grep 'BAT'`

Lilypond in Debian Stretch

lilypond wasn't included in stretch, but has been backported

add

deb http://ftp.debian.org/debian stretch-backports main

to /etc/apt/sources.list, and then

sudo apt update
sudo apt-get -t stretch-backports install lilypond

To install a new version of Racket on an old version of Debian

Running Debian 8 which has Racket 2.1.

Trying to work through

http://io.livecode.ch/learn/gregr/icfp2017-artifact-auas7pp

for which there is a Racket Package

2.1 is not good enough, need Racket 2.6

Check out:

https://backports.debian.org/Instructions/

$ su

# echo "deb http://ftp.debian.org/debian jessie-backports main" >> /etc/apt/sources.list

# apt update

# apt-get -t jessie-backports install racket

Now have Racket 2.7, which is good enough.

grep just highlight

https://stackoverflow.com/questions/7393906/highlight-text-similar-to-grep-but-dont-filter-out-text#7394821

Trick is to use ^ to every line with a start-of-line. Since that's unprintable it won't get highlighted.

So to list all the files with arista in the name, but highlight the objects:

find . -name "*arista*" | grep -E '^|\.o|.so'