Martin Ritter MIB1700

ZSH CheatSheet

This is a cheat sheet for how to perform various actions to ZSH, which can be tricky to find on the web as the syntax is not intuitive and it is generally not very well-documented.

Strings

Description	Syntax
Get the length of a string	`${#VARNAME}`
Get a single character	`${VARNAME[index]}`

#Git: checkout a single file from a specific commit

When we need to retrieve a single file from an old commit, because the current one got deleted or broken and then commited by mistake, use:

git checkout <COMMIT#> <path/to/the/messed/up/file>

To get the COMMIT#:

	git rev-list --objects --all \|
	git cat-file --batch-check='%(objecttype) %(objectname) %(objectsize) %(rest)' \|
	sed -n 's/^blob //p' \|
	sort --numeric-sort --key=2 \|
	cut -c 1-12,41- \|
	$(command -v gnumfmt \|\| echo numfmt) --field=2 --to=iec-i --suffix=B --padding=7 --round=nearest

	#from https://stackoverflow.com/questions/10622179/how-to-find-identify-large-commits-in-git-history

	function startPiP() {
	var videos = document.getElementsByTagName('video');
	for(vid in videos) {
	if(videos[vid].src) videos[vid].webkitSetPresentationMode("picture-in-picture");
	}
	}
	startPiP();

	for f in *
	do
	if [[ $f == *.png ]]
	then
	#name of current file
	name="${f%.png}"

	convert "${f}" -bordercolor white -border 10 \
	\( +clone -background black -shadow 75x25+10+10 \) \
	+swap -background none -layers merge +repage \

	for f in *
	do
	ffmpeg -i "$f" -c:a mp3 -ab 192k "${f%.*}".mp3
	done

	#assumes that all files in the folder are audio files or video files containing audio!

	git rm -r --cached .
	git add .
	git commit -m "removed useless files after .gitignore update"


	ffmpeg -y -i "$file1" -i "$file2" -filter_complex acrossfade=ns="$crossFormat":c1=hsin:c2=hsin output.aiff

	#crossFormat = num samples to use in crossfade