make use of $! to prevent requirement of /dev/urandom

NOTE: generation without it causes large output numbers

LICENSE

@@ -1,19 +1,24 @@
-MIT License Copyright (c) <year> <copyright holders>
+This is free and unencumbered software released into the public domain.
 
-Permission is hereby granted, free of charge, to any person obtaining a copy
+Anyone is free to copy, modify, publish, use, compile, sell, or
-of this software and associated documentation files (the "Software"), to deal
+distribute this software, either in source code form or as a compiled
-in the Software without restriction, including without limitation the rights
+binary, for any purpose, commercial or non-commercial, and by any
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+means.
-copies of the Software, and to permit persons to whom the Software is furnished
-to do so, subject to the following conditions:
 
-The above copyright notice and this permission notice (including the next
+In jurisdictions that recognize copyright laws, the author or authors
-paragraph) shall be included in all copies or substantial portions of the
+of this software dedicate any and all copyright interest in the
-Software.
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
 
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
-WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
-OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+For more information, please refer to <https://unlicense.org>

README

@@ -1,3 +1,5 @@
-----
+---
-# psh-prng
+psh-prng
 -- an attempt at pure POSIX sh random number generation
+-- 100% POSIX compliant; if /dev/urandom is missing PIDs are used
+---

README.md

@@ -1,5 +1,7 @@
 ```
-----
+---
-# psh-prng
+psh-prng
 -- an attempt at pure POSIX sh random number generation
+-- 100% POSIX compliant; if /dev/urandom is missing PIDs are used
+---
 ```

ran

@@ -4,25 +4,18 @@ mseed() {
   [ -c /dev/urandom ] && {
     read -r seed < /dev/urandom # read a single line of urandom
     seed=${#seed}
-  } || { # otherwise generate a seed by counting stuff
+  } || { # otherwise generate a seed using pids
-    n=0;
+    echo "!! WARNING: /dev/urandom IS MISSING -- HARDWARE RANDOMNESS CANNOT BE USED -- USING PID !!" >&2
-    [ -x /bin/ ] && { # if we can access /bin count the files in it
+    echo "!!                              -- CONTINUE AT YOUR OWN RISK --                        !!" >&2
-      for i in /bin/*; do
+    : & wait; o="$!"; for i in 1 2 3 4 5; do
-        [ -f "$i" ] && : $((n+=1))
+      : & wait # generate new $!
-      done
+      o=$((o%o+$!*o))
-    }
+    done
-    [ -x /tmp/ ] && {
+    for i in 1 2 3; do
-      for i in /tmp/*; do
+      : & wait
-        [ -e "$i" ] && : $((n+=1))
+    done
-      done
+    seed="$((o%o+$!*${#o}))" # greatly shorten seed
-    }
+    # large seeds produce large numbers = more randomness
-    [ -x /var/ ] && {
-      for i in /var/*; do
-        [ -e "$i" ] && : $((n+=1))
-      done
-    }
-    : $((n+=${#PWD})); : $((n+=${#0}))
-    seed="${n:-100}"
   }
 } # make seed
 mseed
@@ -109,7 +102,21 @@ done
 # the idea here is, a single line of urandom's output is (almost) random data
 # thus count the length of said line, grab it's last digit, and add it (((a*seed)+p)%m)*m  
 # -- o should be any number 0-9
-read -r o < /dev/urandom; o=${#o}
+[ -c /dev/urandom ] && {
+  read -r o < /dev/urandom
+  o="${#o}"
+} || {
+  echo "!! WARNING: /dev/urandom IS MISSING -- HARDWARE RANDOMNESS CANNOT BE USED -- USING PID !!" >&2
+  echo "!!                              -- CONTINUE AT YOUR OWN RISK --                        !!" >&2
+  # warn about lack of hardware randomness
+  : & wait
+  o="$!" # pid is "RANDOM"
+  for i in 1 2 3; do
+    : & wait
+  done # 3 pid calls
+  o="$((o%o*o+$!))" # this allows the last digit to actually be random
+}
+
 until [ "${#o}" -eq 1 ]; do
   o=${o#?}
 done #; echo "$o -"