Generating Random Number in Child Process using Fork
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 again calls the srand.. any fix for that ?
This is my working code (just the rand function messing up)
Hi!
IN THE FOLLOWING PROGRAM THE VALUE OF j REMAINS UNCHANGED . WHY ? IF I WANT A VARIABLE VALUE TO CHANGE LIKE THIS , IS THERE ANY WAY TO DO IT ?
Or do we have to use shared memory variables?
main()
{
int return_pid, i, total;
int j=1;
total = TOTALRECS+1;
for... (2 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)
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 ${SEED%.*}
Now, in online examples... (4 Replies)
Hi everyone
i am very new to linux , working on bash shell.
I am trying to solve the given problem
1. Create a process and then create children using fork
2. Check the Status of the application for successful running.
3. Kill all the process(threads) except parent and first child... (2 Replies)
Hi there I am trying to generate a random number between 40 and 70 using the shell here is my code so far and it keeps going above 70. all help much appreciated!
comp=$(( RANDOM%70+40 ))
echo $comp (4 Replies)
Having a hard time with this. Very new to scripting and linux. Spent all sunday trying to do this. Appreciate some help and maybe help breaking down what the syntax does.
Create a Bash program. It should have the following properties
• Creates a secret number between 1 and 100
i. The... (3 Replies)
Hi Guys and gals...
As you know I am getting to grips with POSIX and hit this stumbling block.
Generating two random numbers 0 to 255 POSIXly. Speed in not important hence the 'sleep 1' command.
I have done a demo that works, but it sure is ugly! Is there a better way?
#!/bin/sh
# Random... (12 Replies)
Hi All
Below code is working as expected but creating too many child processes when the url is not up and every minute that process is sending false email alerts
any help with the logic not to generate child process and not to send duplicate alerts
app="https://url"
appresult=$(wget... (2 Replies)
Discussion started by: srilinux09
2 Replies
LEARN ABOUT REDHAT
srand
RAND(3) Linux Programmer's Manual RAND(3)NAME
rand, srand - random number generator.
SYNOPSIS
#include <stdlib.h>
int rand(void);
void srand(unsigned int seed);
DESCRIPTION
The rand() function returns a pseudo-random integer between 0 and RAND_MAX.
The srand() function sets its argument as the seed for a new sequence of pseudo-random integers to be returned by rand(). These sequences
are repeatable by calling srand() with the same seed value.
If no seed value is provided, the rand() function is automatically seeded with a value of 1.
RETURN VALUE
The rand() function returns a value between 0 and RAND_MAX. The srand() returns no value.
NOTES
The versions of rand() and srand() in the Linux C Library use the same random number generator as random() and srandom(), so the lower-
order bits should be as random as the higher-order bits. However, on older rand() implementations, the lower-order bits are much less ran-
dom than the higher-order bits.
In Numerical Recipes in C: The Art of Scientific Computing (William H. Press, Brian P. Flannery, Saul A. Teukolsky, William T. Vetterling;
New York: Cambridge University Press, 1992 (2nd ed., p. 277)), the following comments are made:
"If you want to generate a random integer between 1 and 10, you should always do it by using high-order bits, as in
j=1+(int) (10.0*rand()/(RAND_MAX+1.0));
and never by anything resembling
j=1+(rand() % 10);
(which uses lower-order bits)."
Random-number generation is a complex topic. The Numerical Recipes in C book (see reference above) provides an excellent discussion of
practical random-number generation issues in Chapter 7 (Random Numbers).
For a more theoretical discussion which also covers many practical issues in depth, please see Chapter 3 (Random Numbers) in Donald E.
Knuth's The Art of Computer Programming, volume 2 (Seminumerical Algorithms), 2nd ed.; Reading, Massachusetts: Addison-Wesley Publishing
Company, 1981.
CONFORMING TO
SVID 3, BSD 4.3, ISO 9899
SEE ALSO random(3), srandom(3), initstate(3), setstate(3)GNU 1995-05-18 RAND(3)