Appreciated. And sorry. I'm not a Mac person. Did you try it with the seed call?
1) There is no need to apologise, you gave a good method and I found its foibles.
2) We have both learnt something from this thread, me moreso than you.
3) Yes I did try it with 'srand()' and now I think understand why 'while(1)' is used. See EDIT: in post #7.
4) It shouldn't matter about the platform if the code is fully 'sh' compliant.
Boy oh boy, keeping everything POSIX compliant is difficult; especially as I like to do animations and hit the hardware, (bang the metal <wink>).
All I want now is the answer to edited section in my post #3.
In most implementations of awk, random number sequences start are seeded with a constant value (not with the current time) unless you call srand() before calling rand() the first time. (So, as you saw when invoking awk once a second to just produce two random numbers without calling srand() you frequently end up with with the same pair of random numbers every time you call awk. Furthermore, calling srand() with no operand supplies the number of Seconds since the Epoch as an integer number of seconds as the seed value in all but one implementation of awk that I know of. So, if awk is invoked to generate two random numbers calling srand() but without sleeping between invocations of awk you may get the same pair of random numbers a few times until the time in seconds changes.
While it is true that the while(1) loop in the following awk script is an infinite loop, it will only go through that loop a few hundred times before the pipe to the shell fills up (putting awk to sleep for a while). And, yes, byteone and bytetwo are only defined in the while do loop, it was my assumption that whatever you want to do with those variables will be placed in that loop replacing the echo command.
But, obviously, if a known number of pairs of random numbers are wanted, the while(1) can be changed to a while(cnt++<num) loop, or the shell's while read loop can break or exit when it is done instead of using sleep or just continuing to process the next pair of random numbers.
Thanks for the info, it is all logged down in the old grey matter for future use.
As for while(1) I assumed that it was filling up a buffer of some kind but never guessed that it was the pipe, | , that it was filling up.
Clever idea that one. (I love lateral thinking.)
I assumed also - like in Python - that while(1) is the equivalent of while(True): . Both (1) and (True) are valid in Python even in Python's latest guise.
Python has not deprecated the (1) which goes back to the start of the Python project.
LBNL, I got the idea of my original ugly code from the WWW from many sources and no-one considered that '/dev/urandom' was NOT in the POSIX specifications. Even the WWW can give answers that are effectively false, so......
......I now consider this thread _solved_ and thanks again Don, you saved the day.
Hi Don...
Thanks for the info, it is all logged down in the old grey matter for future use.
As for while(1) I assumed that it was filling up a buffer of some kind but never guessed that it was the pipe, | , that it was filling up.
Clever idea that one. (I love lateral thinking.)
I assumed also - like in Python - that while(1) is the equivalent of while(True): . Both (1) and (True) are valid in Python even in Python's latest guise.
Python has not deprecated the (1) which goes back to the start of the Python project.
LBNL, I got the idea of my original ugly code from the WWW from many sources and no-one considered that '/dev/urandom' was NOT in the POSIX specifications. Even the WWW can give answers that are effectively false, so......
......I now consider this thread _solved_ and thanks again Don, you saved the day.
Hello wisecracker,
In Python3.4 you could try following and let me know if this helps you.
Following will be output on same.
Thanks,
R. Singh
I can't use Python in any guise as I have no idea if it is part of ALL *NIX installations.
Similarly Perl, but I have no knowledge of Perl programming anyhow.
It had to be purely POSIX 'sh' compliant and it became much more difficult than I had imagined. As Don so succinctly put it WRT my Post #1:-
Quote:
"/dev/urandom" is not specified by POSIX. So, besides being ugly, it doesn't really conform to POSIX.
There is also the fact that, is Python subject to POSIX compliance?
Again, I have no idea, so rather than use it I avoided it...
In fact I have all but abandoned Python in preference to shell scripting now.
And finally, all my Python code that I have uploaded to the WWW usually works form Python 1.4.0, (Classic AMIGA 1200(HD)), to Python 3.4.3, my latest on various current platforms without modification. This is also seriously difficult to do!
However thanks for your input...
Last edited by wisecracker; 07-19-2016 at 07:03 AM..
Hi all...
Apologies for any typos, etc...
This took a while but it didn't beat me...
Although there are many methods of generating random numbers in a POSIX shell this uses integer maths and a simple C source to create an executable to get epoch to microseconds accuracy if it is needed. I take... (8 Replies)
Hi,
How can I generate a string of random characters (alpha+numeric) of a particular length ?
For e.g. for
n=5, output = 'kasjf'
n=10, output = 'hedbcd902k'
Also, please let me know if random (valid) dates could also be generated.
Thanks (7 Replies)
Having a hard time with this. Very new to scripting and linux. Spent all sunday trying to do this. Appreciate some help and maybe help breaking down what the syntax does.
Create a Bash program. It should have the following properties
• Creates a secret number between 1 and 100
i. The... (3 Replies)
Hi there I am trying to generate a random number between 40 and 70 using the shell here is my code so far and it keeps going above 70. all help much appreciated!
comp=$(( RANDOM%70+40 ))
echo $comp (4 Replies)
Hello All, I am stuck up in a program where the rand functions ends up giving all the same integers. Tried sleep, but the numbers turned out to be same... Can anyone help me out how to fix this issue ? I have called the srand once in the program, but I feel like when I call fork the child process... (5 Replies)
Im new to C, and Im having a hard time getting a random number.
In bash, I would do something similar to the following to get a random number;
#!/bin/bash
seed1=$RANDOM
seed2=$RANDOM
seed3=$RANDOM
SEED=`expr $seed1 * $seed2 / $seed3`
echo ${SEED%.*}
Now, in online examples... (4 Replies)
Hi,
I am having trouble with generating random numbers. can this be done with awk?
So I have a file that looks like this:
23 30
24 40
26 34
So column1 is start and column2 is end. I want to generate 3 random #'s between start and stop:
So the output will look like this:
... (9 Replies)