How to generate a random integer with specific range(for example, from 1 to 1000)?
Also, how to convert a floating point number into a integer? (2 Replies)
I want to be able to generate a random number within a korn shell script..
Preferably i would like to be able to state how many digits should be in this random number... ie 4 digits or 5 digits etc
Any ideas? (2 Replies)
Hello All...
Can someone help me generate a random password which will be 7 characters long which contains alpha-numeric characters using shell script.
I am looking to store the output of the script that generates the password to a variable within a script and use it as the password.
... (5 Replies)
I need a function to generate a random alphanumeric password in C code. It needs to be between 6-8 characters and follow the following rules:
Reject if same char appears # time: 4 or more
Reject if same char appears consecutively: 3 or more
I have the following random password working for... (2 Replies)
I saw this formula to generate random number between two specified values in shell script.the following.
$(((RANDOM%(max-min+divisibleBy))/divisibleBy*divisibleBy+min))
Give a example in book.
Generate random number between 6 and 30.like this.
$(((RANDOM%30/3+1)*3))
But I have a... (1 Reply)
Hi All,
I have extracted some report from database for few activities done.
Now I have a requirement to add some random time(In range of 10-35) in front of each activity.
Can be generated random numbers in any bash/sh shell within a given number range, let's say in between 10-30.
... (10 Replies)
Dear all,
I have a question. I have a txt file say 4000 rows X 1800 Column. I 'd like to creat a new column as the first column which is a column of random numbers (n=4000)
thanks a lot!
Lin (2 Replies)
Need to use dd to generate a large file from a sample file of random data. This is because I don't have /dev/urandom.
I create a named pipe then:
dd if=mynamed.fifo do=myfile.fifo bs=1024 count=1024
but when I cat a file to the fifo that's 1024 random bytes:
cat randomfile.txt >... (7 Replies)
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)
Discussion started by: wisecracker
8 Replies
LEARN ABOUT BSD
initstate
RANDOM(3) Library Functions Manual RANDOM(3)NAME
random, srandom, initstate, setstate - better random number generator; routines for changing generators
SYNOPSIS
long random()
srandom(seed)
int seed;
char *initstate(seed, state, n)
unsigned seed;
char *state;
int n;
char *setstate(state)
char *state;
DESCRIPTION
Random uses a non-linear additive feedback random number generator employing a default table of size 31 long integers to return successive
pseudo-random numbers in the range from 0 to (2**31)-1. The period of this random number generator is very large, approximately
16*((2**31)-1).
Random/srandom have (almost) the same calling sequence and initialization properties as rand/srand. The difference is that rand(3) pro-
duces a much less random sequence -- in fact, the low dozen bits generated by rand go through a cyclic pattern. All the bits generated by
random are usable. For example, ``random()&01'' will produce a random binary value.
Unlike srand, srandom does not return the old seed; the reason for this is that the amount of state information used is much more than a
single word. (Two other routines are provided to deal with restarting/changing random number generators). Like rand(3), however, random
will by default produce a sequence of numbers that can be duplicated by calling srandom with 1 as the seed.
The initstate routine allows a state array, passed in as an argument, to be initialized for future use. The size of the state array (in
bytes) is used by initstate to decide how sophisticated a random number generator it should use -- the more state, the better the random
numbers will be. (Current "optimal" values for the amount of state information are 8, 32, 64, 128, and 256 bytes; other amounts will be
rounded down to the nearest known amount. Using less than 8 bytes will cause an error). The seed for the initialization (which specifies
a starting point for the random number sequence, and provides for restarting at the same point) is also an argument. Initstate returns a
pointer to the previous state information array.
Once a state has been initialized, the setstate routine provides for rapid switching between states. Setstate returns a pointer to the
previous state array; its argument state array is used for further random number generation until the next call to initstate or setstate.
Once a state array has been initialized, it may be restarted at a different point either by calling initstate (with the desired seed, the
state array, and its size) or by calling both setstate (with the state array) and srandom (with the desired seed). The advantage of call-
ing both setstate and srandom is that the size of the state array does not have to be remembered after it is initialized.
With 256 bytes of state information, the period of the random number generator is greater than 2**69 which should be sufficient for most
purposes.
AUTHOR
Earl T. Cohen
DIAGNOSTICS
If initstate is called with less than 8 bytes of state information, or if setstate detects that the state information has been garbled,
error messages are printed on the standard error output.
SEE ALSO rand(3)BUGS
About 2/3 the speed of rand(3C).
4.2 Berkeley Distribution September 29, 1985 RANDOM(3)