random_string_generator

#!/bin/bash
# +-----------------------------------------------------------------------------------------+
# | Bash random string generator                                                            |
# | Handy for passwords or keys                                                             |
# |                                                                                         |
# |                                                                                         |
# | November 2011 flip hess flip@nerdmetbril.nl                                             |
# +-----------------------------------------------------------------------------------------+

# Global variables:

PATH='/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin'
SCRIPT_PATH="${0}"
ARGS="${#}"
CHARSET="A-Za-z0-9!@\#\$%^&*\(\)_+=-[]><~}{"
# CHARSET="[A-Za-z0-9]"
# CHARSET="[A-Za-z]"
# CHARSET="[0-9]


# Functions:

  # exit function
  function die()
  {
    echo "${1}"
    exit 1
  }

  # Shows usage function.
  function fShowUsage()
  {
    echo -e "\n\
    Usage: ${SCRIPT_PATH} <total chars>\n\
         Create a set string of random characters
         Handy for passwords, keys etc.
         November 2011 flip@nerdmetbril.nl\n\
    "

    return 0
  }

  # Create random string
  function fRandom()
  {
   local LENGTH="${1}"

   # check for arguments:
   [ ${#} = 1 ] || { fShowUsage ; exit 1; }

   # check if arg only contains numbers:
   CHECK=$( echo ${LENGTH} | tr -d "[0-9]")
   [ -z ${CHECK} ] || { fShowUsage ; exit 1; }

   # GENERATE STRING
   PASS="$( < /dev/urandom tr -dc "${CHARSET}" | head -c "${LENGTH}" )"

   # Output
   echo -e "Your ${LENGTH} characters string is:\n ${PASS}"
}

 # Start the program:
  fRandom "${@}"

 # Exit with previous return code:
  exit "${?}"