How compatible is your Unix with the original one?

unix-compatible.sh

#!/usr/bin/env bash

TEMPFILE=/tmp/unixcount
exist=0
notexist=0

echo 0 0 > $TEMPFILE

curl "https://raw.githubusercontent.com/dspinellis/unix-v4man/master/man0/ptxx"|
grep "(I)"|
sed -e 's/.*\"\(.*\)(I).*/\1/'|
sort|
uniq|
while read cmd; do
  if hash "$cmd" 2>/dev/null; then
    echo "$cmd exists";
    exist=$((exist+1))
  else
    echo "$cmd does not exist"
    notexist=$((notexist + 1))
  fi
  echo $exist $notexist > $TEMPFILE
done

exist=`cat $TEMPFILE|cut -f1 -d ' '`
notexist=`cat $TEMPFILE|cut -f2 -d ' '`
total=$(($exist+$notexist))
perc=`echo "scale=2; $exist / $total * 100"| bc -l`

echo
echo "Your system (`uname -v`) is $perc% UNIX"

unlink $TEMPFILE

Ha!

Ubuntu 17.10: Your system (#19-Ubuntu SMP Wed Oct 11 18:35:14 UTC 2017) is 71.00% UNIX

But your script has a problem: I have if, and yet it is displayed as non-existent.

Indeed. if is a bash built-in, which hash does not detect.