Bash decimal to base 62 conversion
I do really appreciate the solution you came up with, and I guess there's no way around it straight with bash. Here's the little point you've missed:
BASE62=($(echo {0..9} {a..z} {A..Z}))for i in $(bc <<< "obase=62; 9207903953"); do echo -n ${BASE62[$(( 10#$i ))]}done && echoOutput:
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function base62encode() { bc<<<"obase=62;$1" | awk '{for (i=1; i<=NF; i++) printf "%c", $i+(($i<10)?48:(($i<36)?87:29))}'}bc<<<"obase=62;$1"converts to a sequence of space prefixed decimal numbers from 00 to 61- then offset each digit into ASCII table and convert to character with awk's printf
Or without the for loop:
function base62encode() { bc<<<"obase=62;$1" | awk 'BEGIN{RS=" +"}/./{printf "%c", $1+(($1<10)?48:(($1<36)?87:29))}';}
Or without bc and with arbitrary base:
function baseXencode() { awk 'BEGIN{b=split(ARGV[1],D,"");n=ARGV[2];do{d=int(n/b);i=D[n-b*d+1];r=i r;n=d}while(n!=0);print r}' "$1" "$2"}function base62encode() { baseXencode 0123465789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ "$1"}