Except, of course, that you'll get a 1-digit random number about 10 times out of a thousand (replacing 4 spaces with 2 characters) and a 2-digit random number about 90 times out of a thousand (replacing 4 spaces with 3 characters).
Ooops. You are right (and that's trivial to fix). Unless we are happy with leading zeroes in the random number, we should use
instead.....
Is anyone know some scripts to generate random number without repetition using bash; for example generate 10 different random numbers.
Thanks (8 Replies)
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)
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
chrno start end... (3 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)
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.
i'm having problem since the PID on the string is dynamic. It may be 2-5 digits or more.
... (5 Replies)
Can I insert rows based on line numbers. Say If I need to insert 1 or more rows in a file from line number 10. Can I do that in UNIX
I have a file something like
A
B
C
D
E
F
After row C, I wanted to add 2 records as X and Y. I have the line number after C as my reference. Can I... (2 Replies)
Hi All,
I have one file name called test.txt and its having numbers inside the file.I need to identified next available number with use of unix shell scipt and have to update next available number with use of unix shell script.
Example:-
cat test.txt
5001
5002
5003
5005
7000
7001
... (5 Replies)
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
... (3 Replies)
Discussion started by: renegade755
3 Replies
LEARN ABOUT REDHAT
urandom
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)