rand: Support from-to range.

This commit is contained in:
Ole Tange 2017-06-28 13:21:31 +02:00
parent 329ed04861
commit ddd10e4c13

View file

@ -10,7 +10,7 @@ rand - Generate (pseudo-)random data
=head1 SYNOPSIS
B<rand>
B<rand> [[I<from>] I<to>]
=head1 DESCRIPTION
@ -22,6 +22,10 @@ faster (400 MB/s on hardware from 2013).
The quality is lower as there are only 2^256 different tables (this is
still around the number of atoms in the visible universe).
If I<to> is given, numbers will be integers from 0 to I<to>.
If I<from> is also given, numbers will be integers from I<from> to I<to>.
=head1 EXAMPLE
@ -30,9 +34,16 @@ Overwrite a harddisk with random data:
rand >/dev/sda
=head1 EXAMPLE
100 random numbers from 1000 to 1999:
rand 1000 1999 | head -n 100
=head1 AUTHOR
Copyright (C) 2016 Ole Tange,
Copyright (C) 2017 Ole Tange,
http://ole.tange.dk and Free Software Foundation, Inc.
@ -74,5 +85,34 @@ randfunc() {
< /dev/zero openssl enc -aes-128-ctr -K $key -iv $iv 2>/dev/null
}
export -f randfunc
# Boost performance by running 1 per CPU core
eval parallel -u randfunc ::: {1..$(parallel --number-of-cores)}
ints() {
from=$1
to=$2
# Allow up to 2^64
perl -e '$diff='$to-$from'+1;
$factor = 2**64/$diff;
while(sysread(STDIN,$buf,65536)) {
print map { (int($_ / $factor) + '$from'),"\n" } unpack("Q*",$buf);
}'
}
export -f ints
randints() {
randfunc | ints "$@"
}
export -f randints
if [ "$1" == "" ] ; then
# Boost performance by running 1 per CPU core
eval parallel -u randfunc ::: {1..$(parallel --number-of-cores)}
else
# $1 set => numerical
if [ "$2" == "" ] ; then
# 0 .. $1
eval parallel --lb randints 0 $1 ::: {1..$(parallel --number-of-cores)}
else
# $1 .. $2
eval parallel --lb randints $1 $2 ::: {1..$(parallel --number-of-cores)}
fi
fi