obscure.sh

obscure.sh

#!/bin/bash

# obscure provides a command that will obscure any text passed in via standard input
#
# obscure replaces all the text passed into standard input, save the first five characters,
# with random symbols by default. It was developed as a way to show sensitive information
# (auth tokens, etc.) to the audience during presentations. It lets you prove, e.g., that
# an environment variable is set without disclosing the full contents of the variable.
#
# Example usage: $ echo $MYVAR | obscure
#
# Adapted from: https://github.com/paddycarver/obscure

obscure () {
  type_of_mask=${MASK_TYPE:-random}
  num_chars_to_show=${SHOW_CHARS:-5}
  IFS= read -r str
  (( num_chars_to_mask = ${#str} - ${num_chars_to_show} ))
  echo -n "${str:0:${num_chars_to_show}}"

  case "$type_of_mask" in
    snip)
      echo '<snip>'
      ;;
    xxx)
      for (( i = 0 ; i < ${num_chars_to_mask} ; i++ )); do
        echo -n 'x'
      done
      ;;
    *)
      echo -n "$(cat /dev/urandom | LC_CTYPE=C tr -cd "[:graph:]" | head -c ${1:-${num_chars_to_mask}})"
      ;;
  esac
  echo
}

obscure