TL;DR → The main problem is coming up with a way to reorder an array non-randomly but without introducing bulky code. Like the effect of shuffling a deck of cards in a deterministic cheating way.

Full background:

I would like to generate reference numbers for letters sent via postal mail. An sqlite db is used to track the sequence numbers (but not the reference numbers). This is the bash code I have so far:

 undefined

    
typeset -a symbolset=(a b c d e f g h   j k   m n   p q r s t u v w x y z     2 3 4 5 6 7 8 9)
ln_symbolset=${#symbolset[@]}; # 41 is the answer, not 42
itemseq=$(sqlite3 ltr_tracking.db "select max(counter) from $tbl;")
printf '%s\n' "next letter reference number is: $(date +%Y)-${symbolset[$((itemseq / ln_symbolset))]}${symbolset[$((itemseq % ln_symbolset))]}"

  

An array is defined with alphanumeric symbols, taking care to eliminate symbols that humans struggle to distinguish (e.g. 1l0o). Then integer div and mod operations produce a two character number which is the

ps auxf | sort -nr -k 4 | head -5

(As I shamelessly lifted this from DistroTube, I may as well go the whole hog and suggest you alias it to mem5)

lsblk -i --tree -o name,fstype,uuid,path,size,fsuse%,fsused,label,mountpoint #bash #code #snippet