10 More Discussions You Might Find Interesting
1. HP-UX
Hi,
In our HP-UX B.11.11. I could not find dev/urandom and dev/random
Are all pseudo-devices implemented as device drivers, or in need to run /configure some package to install the package to have dev/urandom.
Please help (4 Replies)
Discussion started by: rashi
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2. Homework & Coursework Questions
Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted!
Write a shell script that will take the sum of two random number?
Ex: Random n1 +Random n2 = result
i tries to write it but i had some dufficulties
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3. Shell Programming and Scripting
i want to generate a random number through a script, and even if anyone reads the script, they wont be able to figure out what the random number is. only the person who setup the script would know it.
something like this could work: random
the full thread is here:
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Discussion started by: SkySmart
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4. Shell Programming and Scripting
I have a for loop that cycles twice and generates 1 random number for each pass through. I would like to be able to store the two numbers to use later for arithmetics. Is there a way to do that? Right now I can only seem to use the last random number for anything. Thanks. (4 Replies)
Discussion started by: AxlVanDamme
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5. Shell Programming and Scripting
Hi Can someone help me with this one?
I have string..
(PROC_PROC_ID == 12183) <--PID is dynamic
and i want to replace the PID number with whatever PID from
/opt/hpws/apache32_2/logs/httpd.pid file.
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6. Shell Programming and Scripting
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
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7. Shell Programming and Scripting
Hi Guys I have a script to find Ranomd numbers. But I want to make the file to produce more random. Could u guys help me plz.
In this Script I have the code that generates random in for loop and the range I have specified in my %chromlength
input and out put will be like this
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8. Shell Programming and Scripting
Hello All,
I want to make a simple script which generate random number from 0 to 1000.
and simply display it.
Plz HELP!!!!!!
Regards,
Waqas Ahmed (2 Replies)
Discussion started by: wakhan
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9. Programming
Hi,
I am currently trying to generate multiple random numbers in C for different variable:-
die1=1+(rand()%5);
die2=1+(rand()%5);
die3=1+(rand()%5);
die4=1+(rand()%5);
But I need to contrain the total of die1, die2,die3 and die4 to be 5 as well. If i insert die1+die2+die3+die4=5, i do... (6 Replies)
Discussion started by: ahjiefreak
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10. UNIX for Dummies Questions & Answers
Is anyone know some scripts to generate random number without repetition using bash; for example generate 10 different random numbers.
Thanks (8 Replies)
Discussion started by: asal_email
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RANDOM(4) Linux Programmer's Manual RANDOM(4)
NAME
random, urandom - kernel random number source devices
DESCRIPTION
The character special files /dev/random and /dev/urandom (present since Linux 1.3.30) provide an interface to the kernel's random number
generator. File /dev/random has major device number 1 and minor device number 8. File /dev/urandom has major device number 1 and minor
device number 9.
The random number generator gathers environmental noise from device drivers and other sources into an entropy pool. The generator also
keeps an estimate of the number of bit of the noise in the entropy pool. From this entropy pool random numbers are created.
When read, the /dev/random device will only return random bytes within the estimated number of bits of noise in the entropy pool.
/dev/random should be suitable for uses that need very high quality randomness such as one-time pad or key generation. When the entropy
pool is empty, reads to /dev/random will block until additional environmental noise is gathered.
When read, /dev/urandom device will return as many bytes as are requested. As a result, if there is not sufficient entropy in the entropy
pool, the returned values are theoretically vulnerable to a cryptographic attack on the algorithms used by the driver. Knowledge of how to
do this is not available in the current non-classified literature, but it is theoretically possible that such an attack may exist. If this
is a concern in your application, use /dev/random instead.
CONFIGURING
If your system does not have /dev/random and /dev/urandom created already, they can be created with the following commands:
mknod -m 644 /dev/random c 1 8
mknod -m 644 /dev/urandom c 1 9
chown root:root /dev/random /dev/urandom
When a Linux system starts up without much operator interaction, the entropy pool may be in a fairly predictable state. This reduces the
actual amount of noise in the entropy pool below the estimate. In order to counteract this effect, it helps to carry entropy pool informa-
tion across shut-downs and start-ups. To do this, add the following lines to an appropriate script which is run during the Linux system
start-up sequence:
echo "Initializing kernel random number generator..."
# Initialize kernel random number generator with random seed
# from last shut-down (or start-up) to this start-up. Load and
# then save 512 bytes, which is the size of the entropy pool.
if [ -f /var/random-seed ]; then
cat /var/random-seed >/dev/urandom
fi
dd if=/dev/urandom of=/var/random-seed count=1
Also, add the following lines in an appropriate script which is run during the Linux system shutdown:
# Carry a random seed from shut-down to start-up for the random
# number generator. Save 512 bytes, which is the size of the
# random number generator's entropy pool.
echo "Saving random seed..."
dd if=/dev/urandom of=/var/random-seed count=1
FILES
/dev/random
/dev/urandom
AUTHOR
The kernel's random number generator was written by Theodore Ts'o (tytso@athena.mit.edu).
SEE ALSO
mknod (1)
RFC 1750, "Randomness Recommendations for Security"
Linux 1997-08-01 RANDOM(4)