LinuxQuestions.org - calling user input in bash script

You have to change the terminal settings to do this. Using stty you can disable the canonical mode and disable the local echo (this is the same effect of read -s suggested by unSpawn). Then you can detect key strokes using the dd command and put the character corresponding to each key into the password. Echo a single asterisk (or a hash, if you prefer) and repeat until the user hits Enter. Finally restore the original settings and have the "recorded" password at your disposal.

Code:

#!/bin/bash

# ------------------------------------------------------------

#  Prompt user for username and password

# ------------------------------------------------------------

read -p "please enter username and press [enter]: " username

echo -n "please enter password and press [enter]: "

# ------------------------------------------------------------

#  Save current terminal settings

# ------------------------------------------------------------

oldstty=$(stty -g)

# ------------------------------------------------------------

#  Disable canonical mode and local echo

# ------------------------------------------------------------

stty -icanon -echo

# ------------------------------------------------------------

#  Get the first keystroke using dd

# ------------------------------------------------------------

key=$(dd bs=1 count=1 2>/dev/null)

# ------------------------------------------------------------

#  While key is not "Enter" store key in the password,

#  echo an asterisk and get another keystroke

# ------------------------------------------------------------

while [ x$key != x$(echo) ]

do

  password=$password$key

  echo -n \*

  key=$(dd bs=1 count=1 2>/dev/null)

done

echo

# ------------------------------------------------------------

#  Restore old terminal settings

# ------------------------------------------------------------

stty "$oldstty"

# ------------------------------------------------------------

#  Check results

# ------------------------------------------------------------

echo $username

echo $password

How to capture keystrokes using dd is taken from example 15-58 of the Advanced Bash Scripting Guide.