The quality of the output of the algorithm is also very sensitive to the value of seed (line 10).
I was well aware of this that is why I used a variable instead of a fixed value inside line 25.
The idea was to use the last byte read as the next "seed" but I didn't pursue it any further. "seed" must always
have a value greater than or equal to 1 and less than or equal to decimal value 256 added to the current byte in use.
(I assumed you guys would see the flaw and correct as you need.)
However if the current byte value would be zero then "seed" would have to be a minimum value of "1".
(This is taken care of with the limitation of fixing "seed" in the script shown.)
Not because of anything to do with binary zero in shell scripting per-se but it would just stop there until the
loop finished and give that character value at that point continuously ( <- if that sentence is lucid enough. ).
Bazza...
EDIT: Made more lucid.
This is a simple way of making it a little better without the complexity of storing the previous and current
bytes read. (Line 26.)
Last edited by wisecracker; 09-21-2013 at 06:27 PM..
Reason: Rewrite to make more lucid...
I am trying to find a way to generate random numbers within a shell script.
Does Solaris have a utility that will generate random numbers?
Thanks in advance.
B (3 Replies)
In my server migration requirement, I need to compare if one file on old server is exactly the same as the corresponding file on the new server.
For diff and comm, the inputs need to be sorted. But I do not want to disturb the content of the file and need to find byte-to-byte match.
Please... (4 Replies)
Hi,
I need to create a table with random sentences. I need lines that are upto 1000 characters in lenght. I need a random sentence generator that will create sentences and output it to a text file. The sentences should be of lenght varying from 1 to 1000.
Does anyone know how this can be... (7 Replies)
Hi,
I need a script that will generate a set of random strings in sequence, with the ability to predetermine the length, quantity, and alphabet of individual string, and to use the outputs of earlier strings in the sequence to define the parameters of later strings. For examples, I might want... (5 Replies)
I want to develop a script of the following form:
#!/bin/bash
# Function 'listen' opens a data stream
# which stores all incoming bytes in
# a buffer, preparing them to be
# grabbed by a following function
# which appears at random
# intervals during the execution of
# the script
... (11 Replies)
A very simple crude sinewave generator.
The file required is generated inside the code, is linear interpolated and requires /dev/audio to work. Ensure you have this device, if not the download oss-compat from your OS's repository...
It lasts for about 8 seconds before exiting and saves a... (5 Replies)
Hello
I created 3 files by:
dd if=/dev/urandom bs=1024 count=1000000 of=./testfile1
dd if=/dev/urandom bs=1024 count=5000000 of=./testfile2
dd if=/dev/urandom bs=1024 count=10000000 of=./testfile3
Now I want to know how to make a change in a specific byte and/or line of theses files? (2 Replies)
Dear UNIX Friends,
I was wondering if there is a random RGB color generator or any function in any unix platforms.
Please share your ideas.
Thanks (2 Replies)
I am using the below to random generate a password but I need to have 2 numeric characters and 6 alphabetic chars
head /dev/urandom | tr -dc A-Za-z0-9 | head -c 8 ; echo ''
6USUvqRB
------ Post updated at 04:43 PM ------
Any Help folks - Can the output be passed onto a sed command to... (9 Replies)
Discussion started by: infernalhell
9 Replies
LEARN ABOUT OPENDARWIN
random
RANDOM(4) BSD Kernel Interfaces Manual RANDOM(4)NAME
random , urandom -- random data source devices.
SYNOPSIS
pseudo-device random
DESCRIPTION
The random device produces uniformly distributed random byte values of potentially high quality.
To obtain random bytes, open /dev/random for reading and read from it.
To add entropy to the random generation system, open /dev/random for writing and write data that you believe to be somehow random.
/dev/urandom is a compatibility nod to Linux. On Linux, /dev/urandom will produce lower quality output if the entropy pool drains, while
/dev/random will prefer to block and wait for additional entropy to be collected. With Yarrow, this choice and distinction is not necessary,
and the two devices behave identically. You may use either.
OPERATION
The random device implements the Yarrow pseudo random number generator algorithm and maintains its entropy pool. Addditional entropy is fed
to the generator regularly by the SecurityServer daemon from random jitter measurements of the kernel. SecurityServer is also responsible
for periodically saving some entropy to disk and reloading it during startup to provide entropy in early system operation.
You may feed additional entropy to the generator by writing it to the random device, though this is not required in a normal operating envi-
ronment.
LIMITATIONS AND WARNINGS
Yarrow is a fairly resilient algorithm, and is believed to be resistant to non-root. The quality of its output is however dependent on regu-
lar addition of appropriate entropy. If the SecurityServer system daemon fails for any reason, output quality will suffer over time without
any explicit indication from the random device itself.
Paranoid programmers can counter-act this risk somewhat by collecting entropy of their choice (e.g. from keystroke or mouse timings) and
seeding it into random directly before obtaining important random numbers.
FILES
/dev/random
/dev/urandom
HISTORY
A random device appeared in Linux operating system.
Darwin September 6, 2001 Darwin