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Top Forums UNIX for Dummies Questions & Answers Generating 512MB file with dd using random data Post 302729667 by Don Cragun on Saturday 10th of November 2012 08:14:19 PM
Old 11-10-2012
Add an ampersand at the end of your command to start it in the background:
Code:
dd if=/dev/urandom of=file bs=1MB count=512&

then you can use:
Code:
ls -l file

to see the progress of the dd command (by checking the size of the file reported by ls).
 

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rand(3C)																  rand(3C)

NAME
rand(), rand_r(), srand() - simple random-number generator SYNOPSIS
DESCRIPTION
uses a multiplicative, congruential, random-number generator with period 2^32 that returns successive pseudo-random numbers in the range from 0 to 2^15-1. can be called at any time to reset the random-number generator to a random starting point. The generator is initially seeded with a value of 1. returns a random number at the address pointed to by the randval parameter. The seed parameter can be set at any time to start the random- number generator at an arbitrary point. Note The spectral properties of leave a great deal to be desired. provides a much better, though more elaborate, random-number generator (see drand48(3C)). RETURN VALUE
If seed or randval is NULL, returns 0. Otherwise, returns a psuedo-random integer. EXAMPLES
The following: int x, y; srand(10); x = rand(); y = rand(); would produce the same results as: int x, y, s = 10; x=rand_r(&s); y=rand_r(&s); WARNINGS
Users of should note that rand_r() now conforms with POSIX.1c. The old prototype of is supported for compatibility with existing DCE applications only. SEE ALSO
drand48(3C), random(3M), thread_safety(5), random(7). STANDARDS CONFORMANCE
rand(3C)
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