passgen

#!/bin/bash

PASSLENGTH="10"

while [[ $# > 0 ]]; do
  key="$1"
  shift

  case $key in
      -h|--help)
        echo "usage: passgen [-l length]"
        echo "l : password length min 6 chars"
        return
      ;;
      -l|--length)
        PASSLENGTH=$(($1+0))
        shift
      ;;
  esac
done

[ "$PASSLENGTH" -lt 6 ] && PASSLENGTH="6"

let LEN=0
PASSWORD=""

while [ $LEN -lt $PASSLENGTH ]; do
  R=$((RANDOM % 3))
  case "$R" in
    "0") N=$(((RANDOM % 10)+48));; # 48-57
    "1") N=$(((RANDOM % 26)+65));; # 65-90 
    "2") N=$(((RANDOM % 26)+97));; # 97-122
  esac
  C=`printf "%x" $N`
  PASSWORD=$PASSWORD`printf "\x$C"`
  LEN=${#PASSWORD}
done

echo $PASSWORD