replace jot(1) with os independent shell code

up.sh

@@ -3,7 +3,11 @@
 set -eu
 export POSIXLY_CORRECT=1
 
-jot 50 > tmp.log
+i=1
+while test $i -lt 50; do
+	print $i
+	i=$((i + 1))
+done > tmp.log
 
 (sleep 1; printf "\033[5;2~"; sleep 1; ) \
 	| ./ptty ./scroll tail -fn 50 tmp.log > out.log