genpass.sh

   1 #!/bin/sh
   2 ##
   3 ## Generates a random password (or some other key)
   4 ## Copyright (c) 2005,2007 by Michal Nazarewicz (mina86/AT/mina86.com)
   5 ##
   6 ## This program is free software; you can redistribute it and/or modify
   7 ## it under the terms of the GNU General Public License as published by
   8 ## the Free Software Foundation; either version 3 of the License, or
   9 ## (at your option) any later version.
  10 ##
  11 ## This program is distributed in the hope that it will be useful,
  12 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 ## GNU General Public License for more details.
  15 ##
  16 ## You should have received a copy of the GNU General Public License
  17 ## along with this program; if not, see <http://www.gnu.org/licenses/>.
  18 ##
  19 ## This is part of Tiny Applications Collection
  20 ##   -> http://tinyapps.sourceforge.net/
  21 ##
  22
  23 ##
  24 ## You can specify number of characters password should have as
  25 ## a parameter, eg.;
  26 ##     ./getnpass 100
  27 ##
  28
  29
  30 has_random() {
  31         # shellcheck disable=SC2039
  32         [ -n "$RANDOM" ] && [ "$RANDOM" -ne "$RANDOM" ]
  33 }
  34
  35
  36 if [ -r /dev/urandom ]; then
  37         gen_stream () {
  38                 head -c 40 /dev/urandom
  39         }
  40 elif [ -r /dev/random ]; then
  41         gen_stream () {
  42                 head -c 40 /dev/random
  43         }
  44 elif has_random; then
  45         # shellcheck disable=SC2120
  46         gen_stream () {
  47                 set -- 10
  48                 while [ "$1" -gt 0 ]; do
  49                         # shellcheck disable=SC2039
  50                         printf %04x "$RANDOM"
  51                         set -- $(( $1 - 1 ))
  52                 done
  53         }
  54 else
  55         printf "%s: unable to collect random data\n" "${0##*/}" >&2
  56         exit 1
  57 fi
  58
  59
  60 got_command () { test -n "$(which "$1" 2>/dev/null)"; }
  61
  62 if got_command uuencode; then
  63         gen_pass () {
  64                 printf %s "$(uuencode -m pass | tail -n +2 | head -n 1)"
  65         }
  66 elif got_command md5sum; then
  67         gen_pass () {
  68                 P1=$(head -c 32 | md5sum | cut -c1-32)
  69                 P2=$(head -c 32 | md5sum | cut -c1-32)
  70                 printf %s "$P1" "$P2"
  71         }
  72 elif got_command sha1sum; then
  73         gen_pass () {
  74                 P1=$(head -c 32 | sha1sum | cut -c1-32)
  75                 P2=$(head -c 32 | sha1sum | cut -c1-32)
  76                 printf %s "$P1" "$P2"
  77         }
  78 else
  79         printf "%s: unable to generate random password\n" "${0##*/}" >&2
  80         exit 1
  81 fi
  82
  83
  84
  85 len=${1:-64}
  86 if [ "$len" -gt 0 ]; then
  87         l=$len
  88         while [ "$l" -gt 0 ]; do
  89                 # shellcheck disable=SC2119
  90                 gen_stream | gen_pass
  91                 l=$(( l - 64 ))
  92         done | cut -c "1-$len"
  93 fi