CODEWITHSUNDEEP
bashshellpasswords
Deniz Zoeteman
Deniz Zoeteman

Reputation: 10121

How do I echo stars (*) when reading password with `read`?

What do I need to do for code in Bash, if I want to echo *s in place of password characters (or even just hide the characters completely) when the user types something in using read?

Upvotes: 46

Views: 63432

Answers (10)

yspreen
yspreen

Reputation: 1981

@nxnev's answer didn't quite work for me, at least on macOS. I simplified it a bit, and now it's flawless:

#!/bin/bash

ask() {
    charcount='0'
    prompt="${1}: "
    reply=''
    while IFS='' read -n '1' -p "${prompt}" -r -s 'char'
    do
        case "${char}" in
            # Handles NULL
            ( $'\000' )
            break
            ;;
            # Handles BACKSPACE and DELETE
            ( $'\010' | $'\177' )
            if (( charcount > 0 )); then
                prompt=$'\b \b'
                reply="${reply%?}"
                (( charcount-- ))
            else
                prompt=''
            fi
            ;;
            ( * )
            prompt='*'
            reply+="${char}"
            (( charcount++ ))
            ;;
        esac
    done
    printf '\n' >&2
    printf '%s\n' "${reply}"
}

pwd="$(ask Password)"

echo "Your password is $pwd"

Upvotes: 3

nxnev
nxnev

Reputation: 121

I just made this Bash-specific function based on Dennis Williamson's, Wirone's and Logan VanCuren's answers:

ask() {
  local 'args' 'char' 'charcount' 'prompt' 'reply' 'silent'

  # Basic arguments parsing
  while [[ "${1++}" ]]; do
    case "${1}" in
      ( '--silent' | '-s' )
        silent='yes'
        ;;
      ( '--' )
        args+=( "${@:2}" )
        break
        ;;
      ( * )
        args+=( "${1}" )
        ;;
    esac
    shift || break
  done

  if [[ "${silent}" == 'yes' ]]; then
    for prompt in "${args[@]}"; do
      charcount='0'
      prompt="${prompt}: "
      reply=''
      while IFS='' read -n '1' -p "${prompt}" -r -s 'char'; do
        case "${char}" in
          # Handles NULL
          ( $'\000' )
            break
            ;;
          # Handles BACKSPACE and DELETE
          ( $'\010' | $'\177' )
            if (( charcount > 0 )); then
              prompt=$'\b \b'
              reply="${reply%?}"
              (( charcount-- ))
            else
              prompt=''
            fi
            ;;
          ( * )
            prompt='*'
            reply+="${char}"
            (( charcount++ ))
            ;;
        esac
      done
      printf '\n' >&2
      printf '%s\n' "${reply}"
    done
  else
    for prompt in "${args[@]}"; do
      IFS='' read -p "${prompt}: " -r 'reply'
      printf '%s\n' "${reply}"
    done
  fi
}

It could be used like:

$ ask Username
Username: AzureDiamond
AzureDiamond

$ ask -s Password
Password: *******
hunter2

$ ask First Second Third
First: foo
foo
Second: bar
bar
Third: baz
baz

Upvotes: 2

Dino Dini
Dino Dini

Reputation: 463

If you don't care about it being interactive, you can simply do

read -s pass
echo "$pass" | sed 's/./*/g'

This will show a * for each character of the entered password after enter is pressed.

Upvotes: 4

Logan VanCuren
Logan VanCuren

Reputation: 409

I really liked the answer that Wirone gave, but I didn't like that the backspacing would continue removing characters even back into the "Enter password: " prompt.

I also had some issues where pressing keys too rapidly would cause some of the characters to actually print on the screen... never a good thing when prompting for a password. =)

The following is my modified version of Wirone's answer which addresses these issues:

#!/bin/bash

unset PASSWORD
unset CHARCOUNT

echo -n "Enter password: "

stty -echo

CHARCOUNT=0
while IFS= read -p "$PROMPT" -r -s -n 1 CHAR
do
    # Enter - accept password
    if [[ $CHAR == $'\0' ]] ; then
        break
    fi
    # Backspace
    if [[ $CHAR == $'\177' ]] ; then
        if [ $CHARCOUNT -gt 0 ] ; then
            CHARCOUNT=$((CHARCOUNT-1))
            PROMPT=$'\b \b'
            PASSWORD="${PASSWORD%?}"
        else
            PROMPT=''
        fi
    else
        CHARCOUNT=$((CHARCOUNT+1))
        PROMPT='*'
        PASSWORD+="$CHAR"
    fi
done

stty echo

echo $PASSWORD

Upvotes: 30

7in
7in

Reputation: 1

#!/bin/bash
echo "------------------------------"

n=7
echo " Enter Password :"

for (( i=1;i<n;i++ ))
do
    stty -echo
    read -r -s -n 1 char
    stty echo

    echo -n "*"
    pass+="$char"

done

echo " "
echo " Your password : $pass "

echo ""
echo "-------------------------------"

Upvotes: -1

Wirone
Wirone

Reputation: 3373

I would like to add something to Dennis Williamson's solution:

#!/bin/bash

unset password
echo -n "Enter password: "
while IFS= read -p "$prompt" -r -s -n 1 char
do
    # Enter - accept password
    if [[ $char == $'\0' ]] ; then
        break
    fi
    # Backspace
    if [[ $char == $'\177' ]] ; then
        prompt=$'\b \b'
        password="${password%?}"
    else
        prompt='*'
        password+="$char"
    fi
done

In above example script handles backspace correctly.

Source

Upvotes: 9

Dennis Williamson
Dennis Williamson

Reputation: 360355

As Mark Rushakoff pointed out, read -s will suppress the echoing of characters typed at the prompt. You can make use of that feature as part of this script to echo asterisks for each character typed:

#!/bin/bash
unset password
prompt="Enter Password:"
while IFS= read -p "$prompt" -r -s -n 1 char
do
    if [[ $char == $'\0' ]]
    then
        break
    fi
    prompt='*'
    password+="$char"
done
echo
echo "Done. Password=$password"

Upvotes: 76

Mark Rushakoff
Mark Rushakoff

Reputation: 258358

read -s should put it in silent mode:

-s     Silent mode.  If input is coming from a terminal, characters are not echoed.

See the read section in man bash.

Upvotes: 14

Vinko Vrsalovic
Vinko Vrsalovic

Reputation: 340316

I don't know about stars, but stty -echo is your friend:

 #!/bin/sh 
 read -p "Username: " uname 
 stty -echo 
 read -p "Password: " passw; echo 
 stty echo

Source: http://www.peterbe.com/plog/passwords-with-bash

Upvotes: 5

moonshadow
moonshadow

Reputation: 89115

stty -echo
read something
stty echo

will stop user input being echoed to the screen for that read. Depending on what you are doing with prompts, you may want to add an extra echo command to generate a newline after the read.

Upvotes: 3

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