for finding availibility of ipfs dags

IPFS avail script

#!/bin/sh

# After taking in an IPFS multihash, this script calculates an 'availability' metric by:

# Traversing the hash's dag to find leaves,
# summing the number of providers per leaf (each rounded down to 10 for performance reasons), and
# returning providers/leaves*10.

# since `ipfs pin add` can be run non-recursively, a peer that advertises a given value
# may not actually posess the entire dag, which can be inconvenient.
# This script will return a value between 0-1 indicating how much of the dag can actually be found on the network.

# This was written as a learning experience: It probably works correctly, but definitely not optimally--I don't recommend doing multi-GB hashes.

# I can't put this file's multihash inside itself (that'd be a neat trick), but a mostly commentless version is at:
# QmQr8isLeokaYsXvgvyvFstexkqeiVAiMXuevN6sj9nSJu

# This version (and its hash) can also be found here, where new versions (this is v2018.03.30) may occasionally be posted:
# https://gist.github.com/petersjt014/57debf01da5064f6120616ac983139d0
# If you want to refactor or port it to another language to make it less of a horrorshow, feel free to post a comment there.

# small test hash: QmRCJXG7HSmprrYwDrK1GctXHgbV7EYpVcJPQPwevoQuqF
# SVG diagram of the test hash: Qma8EX27uA27ASxseUuvnLPp8nUHtSDqJJZwCnU4D3uZHn

# more info on graphmd, the tool used to make the diagram:
# https://gateway.ipfs.io/ipfs/QmSrCRJmzE4zE1nAfWPbzVfanKQNBhp7ZWmMnEdbiLvYNh/mdown#/ipfs/QmRFTtbyEp3UaT67ByYW299Suw7HKKnWK6NJMdNFzDjYdX/graphmd/README.md

echo; echo "starting..."
peers=0; leafcount=0

recur(){
echo "recursing"
local refs=$(ipfs refs $1)
local nrefs=$(echo $refs | wc -w); 
echo "--$1--"
if [ $nrefs -eq 0 ]
then
	echo; echo "has no refs (leaf node)"
	((peers+=$(ipfs dht findprovs -n 10 $1 | wc -l)))
	((leafcount+=1))
else
	echo; echo "has $nrefs refs: $refs"
	for x in $refs; do 
		recur $x
	done
fi
}

export -f recur
recur $1
echo "result: $((peers/leafcount*10))"

hash of current version:

QmWzedmwrcDdoAHWLU32iyrVdbVQjVyekoBxrFJckUcVaV