#!/bin/bash 
# random password generator by typedeaF 
# This program has no "real" value other than introducing some bash concepts and putting them to use. 
# to strip the comments: cat this.file | grep -v '^# ' 
 
 
# Sets the maximum size of the password the script will generate 
MAXSIZE=20
 
# Holds valid password characters. I choose alpha-numeric + the shift-number keyboard keys 
# I put escape chars on all the non alpha-numeric characters just for precaution 
array1=(q w e r t y u i o p a s d f g h j k l z x c v b n m Q W E R T Y U I O P A S D 
F G H J K L Z X C V B N M 1 2 3 4 5 6 7 8 9 0 ! @ # $ % ^ & * ( ) 
) 
 
# Used in conjunction with modulus to keep random numbers in range of the array size 
MODNUM=${#array1[*]} 
 
# Keeps track of the number characters in the password we have generated 
pwd_len=0 
 
# Bash's command substitution syntax to store the results of the tput command 
term_clear=$(tput clear) 
 
# Stores the number of lines or rows on the terminal display 
max_lines=$(tput lines) 
 
# Stores the number of columns on the terminal display 
max_cols=$(tput cols) 
 
# Finds the appropriate spot to indent for horizontally centered output 
indent=$(( ((max_cols / 2)) - ((MAXSIZE / 2)) )) 
 
# Finds the vertical center of the terminal. 
line_num=$(( max_lines / 2 )) 
 
# Clear the screen 
echo $term_clear 
 
# The outer while loop starts at 0 and loops till MAXSIZE, creating a passwd char each iteration. 
# The shells $RANDOM variable creates a semi-random unsigned number. This is our entropy. =x 
# x simply holds some random unsigned int that will be used to make the character scramble. 
# 500 was choosen for speed and nothing else. Leave out the mod 500 if you want or change it. 
# The inner loop displays the password characters. Tput keeps the cursor in the proper position. 
# Mod MODNUM keeps the random number inside the size of the array so it doesnt over index. 
while [ $pwd_len -lt $MAXSIZE ] 
do 
  x=$(($RANDOM%500)) 
  y=0 
  while [ $y -lt $x ] 
  do 
    ((y++)) 
    index=$(($RANDOM%$MODNUM)) 
    tput cup $line_num $(( indent + pwd_len )) 
    echo -n "${array1[$index]}" 
  done 
  ((pwd_len++)) 
done 
 
# Place the cursor at the bottom of the screen --where is usually at. 
tput cup $max_lines 0 
 
exit 0